His death was announced by the C. Everett Koop Institute at Dartmouth College, which did not reveal a cause.

Dr. Koop was among the most influential of surgeons general in the nation’s history and assumed a high-profile from the moment he took office, in 1982. Commonly referred to as “America’s family doctor,” he was dubbed by Business Week magazine “America’s real-life Marcus Welby M.D.” Such titles indicate the degree of trust and respect he earned during his tenure as surgeon general, leaving the post in 1989.

His combination of personal candor, professional commitment, and medical competence made him something like a folk hero. At least Homer Simpson thought so. On a 1993 episode of “The Simpsons,” he sang, “For all the latest medical poop/Call Surgeon General C. Everett Koop/Poo poo pa-doop.”

Further contributing to Dr. Koop’s persona was his appearance. He resembled an Old Testament patriarch, with his booming voice and Amish-style whiskers (he grew the beard in middle age to conceal a double chin). He also made a point of wearing the uniform of the public health service (the surgeon general bears a rank equivalent to that of a navy vice admiral), further accentuating his already-commanding bearing. Dr. Koop perfectly fit the bill for an office charged by law “to promote and assure the highest level of health attainable for every individual and family in America.”

An only child, Charles Everett Koop was born on Oct. 14, 1916, in Brooklyn, N.Y. His parents were John Everett Koop, a banker, and Helen (Apel) Koop, a housewife.

“I can’t remember a time when I didn’t want to be a doctor,” he wrote in his autobiography. “I wanted to be a surgeon. The idea of using my mind, then my hands, to heal someone simply fascinated me.” Dr. Koop took this ambition so seriously he began to use scissors left handed (he was right handed) and to tie knots with one hand as preparation for the operating room.

Intellectually precocious, he entered Dartmouth at 16. While there, he picked up his lifelong nickname, “Chick.” More important, he also met a Vassar student named Elizabeth Flanagan. They wed during Dr. Koop’s first year at Cornell Medical School.

Dr. Koop did his internship at Pennsylvania Hospital, in Philadelphia, and was a surgical fellow at the Hospital of the University of Pennsylvania. At the suggestion of a superior there, he switched to the then-nascent field of pediatric surgery, doing a year’s training at Boston Children’s Hospital.

He returned to Philadelphia to become surgeon-in-chief at Children’s Hospital. Only the seventh pediatric surgeon in the country, Dr. Koop pioneered the field. He established America’s first neonatal intensive care unit and was a founder of the Journal of Pediatric Surgery. He later estimated he operated on 17,000 inguinal hernias and 7,000 undescended testicles during his 35 years as a pediatric surgeon, not to mention numerous other procedures, such as three successful separations of Siamese twins. He also taught at the University of Pennsylvania School of Medicine.

A few years after taking up pediatric surgery, Dr. Koop found the somewhat pro forma religiosity of his youth transformed into a fervent faith. “From then on,” he said in a 1982 Saturday Evening Post interview, “there was never any question: I knew I was to practice my Christianity through my surgery.”

The most-publicized form Dr. Koop’s marriage of religion and medicine took was a fierce opposition to abortion. In 1976, he published “The Right to Live, The Right to Die,” a critique of abortion, euthanasia, and infanticide. Three years later, he collaborated with the theologian Francis Schaeffer on a book and film, “Whatever Happened to the Human Race?” Dr. Koop warned against “a progression of thinking in this country from liberalized abortion to infanticide to passive euthanasia to active euthanasia, indeed to the very beginnings of the political climate that led to Auschwitz, Dachau and Belsen.”