Knowing is beautiful. Or is it?

It beckons from MBTA buses and subway station billboards, from Copley Square to Kenmore Square: ''Knowing is beautiful."

It whispers through TV sets, from Green Street to Blue Hill Avenue: ''Knowing is beautiful."

It floats along radio airwaves, from Beacon Hill to Bunker Hill to Fort Hill: ''Knowing is beautiful."

It's the provocative new tagline -- part of a multimillion-dollar, multimedia, multithemed, multinational public-service AIDS education campaign -- aimed at motivating young people to get tested regularly for the HIV virus.

Knowing is beautiful? What a weird choice of words, Boston public health nurse Brianne Fitzgerald thought when she first saw the ad in the subway.

''Knowing is not beautiful," Fitzgerald says now, weeks later. An AIDS counselor and caregiver for nearly 20 years, Fitzgerald recalls a group of her AIDS patients that included a bony, ratty-haired, pock-marked old addict from the JP projects; a tiny baby-doll-like prostitute in the South End who puffed up like a Cabbage Patch Kid before she passed away; and an infant in a Cambodian village whose body was so malnourished and riven by diarrhea that he looked 70, not 7 weeks, before he died.

No, says Fitzgerald, ''It's not beautiful. It's depressing as hell."

Like some others in the field, Fitzgerald, 56, fears that by using such glossy depictions to break the barriers of blasé, the ads are veering into dangerous territory: glamorizing the disease, as she put it; disguising the fact that despite great medical strides, people are still dying from AIDS; dismissing the many who are still living but are shredded by the side effects of their medications, from nausea to nightmares; even loosening safe-sex strictures with its elegant touch.

''We want everything to look nice in our culture," Fitzgerald says. Still, as it sweeps across the country, the ''knowing is beautiful" theme -- a joint effort by Viacom, the media giant, and the Henry J. Kaiser Family Foundation, a nonprofit group that provides information on health issues to the public and policymakers -- is being heaped with praise in some quarters for being a chic public service approach to trying to lower the percentages of those who are infected with HIV but don't know it, now pegged by Kaiser as about 1 in 4 in the United States of those infected.

By eschewing the scary and statistic-driven messages of typically dull public service announcements in favor of a style more reminiscent of a Gap ad -- sensual sepia tones, hip-hop iconography, and an adhesive bandage from a blood test primped up as a beautiful flower-shaped HIV-test trademark -- the media blitz's participants are hoping to turn the clinical into the cool.

''We want it to be fly, to be fresh, to be attractive; people won't pay attention to it if it ain't attractive," says Grammy-winning hip-hop artist Common, the face and voice of the latest ''knowing is beautiful" iteration, in a phone interview from New York. ''Some people will say it's probably a difficult thing to know that you may be [HIV]-positive. . . . It's also an opportunity to take care of yourself during the process and an opportunity for you not to spread anything to anybody else. To me, that's the beautiful side."

Marlon Wallen, a 35-year-old AIDS educator from East Boston who is HIV-positive, thinks the ''knowing is beautiful" ad is spot on. ''At least you know when it started; you can start taking care of your personal health," says Wallen, who did. ''You really need to soften the blow as much as you can. There's enough fear about it."

Others, including AIDS activists and those carrying HIV, say that while the goal of testing is great, the ads may be airbrushing out reality's harsh imperfections by trying to pierce the conventional clutter and reach young people with pop-culture imagery.

''Knowing you're [HIV]-positive so you can get into care -- OK, that's one way to look at it," says Larry Kessler, founding director of the AIDS Action Committee. But, he says, ''not everyone has the same access to care. If you're a person of color, if you're poor, there's a harder time accessing care."

Kessler ponders the catchphrase, ''knowing is beautiful."

''When a person is told they're positive," says Kessler, ''that first blow sometimes can be horrible. I've gone to people's homes and picked up bodies of people who blew their heads off."

Memories not 'beautiful'
When Tonia Hines first saw the ads, she says, they opened old wounds. Her mind crashed into the word ''beautiful" and staggered back to the day seven years before when she learned she was HIV-positive. It continued on to the time soon after that when she considered her bottles of pills and booze and composed a suicide note that, as she recalls it, began: ''I don't think I can handle this. Please take care of my boys," before she was rescued by a relative.

''When you get your first diagnosis, you don't think it's beautiful," says Hines, 38, an outreach worker at the Boston Living Center, a resource hub for people with HIV. ''I haven't heard people say: 'It's beautiful. Girl, it's beautiful.' That, I know I haven't heard."

Hines believes the ads are too slick and sweet to induce testing. ''People relate more to tragedy and bad things," she says, ''than someone getting up and going to work every day and looking sharp."

Because the ''knowing is beautiful" campaign is less than a year old and because the messages featuring Common were only launched in November, after the initial series debuted in June, Davis says the ads' effectiveness haven't been measured with certainty, but has increased hits to the campaign's website.

At a recent roundtable, convened at the Multicultural AIDS Coalition in the South End at the request of City Weekly, a group of young people gave the ads rave reviews.

''I like it," says Jay Cara, 25, of the South End. ''Simple. Short. To the point."

''It has a positive message," says Matthew Truss, 20, of the Back Bay. ''The slogan itself is poetic."

''I like the words," says John Maxwell, 21, of Boston. ''Knowing you're HIV-negative is beautiful; you have a long life to live. Knowing you're HIV-positive is beautiful; you can be treated and live more years than if you didn't know. That's the beauty of the ad."

Maxwell says the ads reinforce his desire to get tested, unlike the typical PSAs that traffic in scare tactics, he says, which might compel someone to get tested, but only once. ''By making it more palatable," he says, ''a person will want to go back and get tested."

Cara scoffs at the suggestion that the ''knowing is beautiful" campaign undermines the message of safe sex. ''I don't see how anyone would say the ad makes you want to engage in risky behavior," he says.

''There's so much information out there," Maxwell says.

Need for a slap in the face
Jhamaul Thomas, 22, of Roxbury, says the ads could use something like a stark hospital setting of AIDS patients to give viewers a slap in the face, presenting the message, ''I need to get tested so I don't end up like that." But of this group of 10, all under age 30, he's the only one seeking an edgier angle.

As Richard Ford, 23, of the South End, says: ''Knowing is beautiful."

Still, Fitzgerald and others fear that the happy glow around the ads could undermine the already difficult task of getting young people to practice safe sex. After all, their thinking goes, how bad can getting infected be if Common, the ambassador for getting tested, who says his own test came back negative, is seen in the ads maxin' and relaxin' while wearing a soulful hat and a flower-shaped bandage as a badge of honor.

''If knowing is beautiful, then living with AIDS is beautiful," Fitzgerald says. ''It negates the message of safe sex."

Officials with Viacom and Kaiser strongly disagree.

''I don't think a billboard with Common wearing a Band-Aid will encourage young people to have unsafe sex," says Julia Davis, Kaiser's associate director of US programs, Entertainment Media Partnerships. ''We wouldn't put out ads we thought were harmful to anyone."

Besides, Davis says, the ''knowing is beautiful" campaign should be seen as one piece of a massive Viacom/Kaiser public-service enterprise.

''No one ad will work for everybody," she says. ''In these ads, we have 10 seconds or 30 seconds. We can't have the entire debate. . . . We feel it's very important to plant that seed."

Since it began in 2003, officials say, the collaboration, called KNOW HIV/AIDS, has tried to lodge AIDS awareness in public consciousness by exploring topics like prevention, stigma, medical care, and testing across Viacom's vast media empire of billboards, radio, and television, from PSAs on MTV to news programs on Nickelodeon to story lines woven into CBS's dramatic prime-time shows, not to mention the website www.knowhivaids.org, which Kaiser says has received more than 10.8 million visitors since the ''knowing is beautiful" ads began. By the end of this year, Viacom says, it will have committed $600 million in media value to the initiative.

With at least half of all new HIV infections in the United States occurring among those under the age of 25, according to Kaiser, the campaign's officials felt they needed something more artistic than drastic to reach young people.

Thus, an adhesive bandage that looks as if it had been plucked from a placid field of clover rather than from a medical lab.

''We wanted to make that Band-Aid almost look like the logo for a hip fashion brand," says David Schiff of the ad agency Crispin Porter + Bogusky, who has served as creative director of the ''knowing is beautiful" campaign.

Thus having the spoken-word artist, Common, be the emissary of AIDS testing, versus some over-the-hill actor droning on darkly about the disease.

''The goal is to get people tested," says Schiff. ''That happens if you can . . . make it an aspirational part of pop culture, the same reason having a Fendi purse would be aspirational for someone, or an association with Common."

Thus the kicker ''knowing is beautiful," which is hopeful and hip, rather than, say, ''knowing is powerful."

''Beauty in the way it's depicted is powerful," Davis says. ''The idea 'beautiful' is big enough to encompass all the things we're trying to say about HIV testing. It's something you do for your partner, something you do to stay healthy, something you do to be productive."

Some may feel alienated
But some fret that, like the young girls with the not-so-svelte figures whose self-worth can slink into a corner when they look at the skinny-minnie fashion-mag models, there will be people alienated by the comeliness of the ''knowing is beautiful" campaign.

''I worry about those who have anything but a beautiful reaction," says Pat Daoust, 56, a Boston nurse, AIDS educator, and Boston Living Center board member, whose daughter is married to Fitzgerald's son.

''By looking at the words and seeing a smiling face, and I don't relate to that, where do I go with my feelings?" she asks. ''I don't know where I go with what I look like and how I feel. Everyone thinks you get infected, you go on drugs, and you're fine. . . . A lot of people are doing extremely well. There's a lot to celebrate. You have to remember that not everyone is having the same experiences. You have to leave room for both sides of the story."

Brenda Bellizeare, 47, who works at the Boston Living Center finding housing for those infected by the AIDS virus, says she doesn't see her own life of being HIV-positive reflected in the ''knowing is beautiful" collection.

There's no model like Bellizeare, whose fingernails have turned brown, whose palms are as rough as sandpaper, who has put 65 pounds on her 5-foot-2-inch frame from taking her medications.

No final scene like the one she had: in a hospital room, holding on to her 3-year-old daughter after a doctor pronounced the child dead from AIDS, guilty tears dripping down for the sickness she'd passed on to her, crying: ''I'm sorry. I'm sorry. I never meant to hurt you."

No thought bubbles over a character's head, expressing the dread she feels whenever another friend dies of AIDS, thinking, ''My time is getting short."

Says Bellizeare: ''There has been nothing, not one thing, beautiful about being diagnosed HIV-positive."