The Celtics said on their web site that Sullinger had successful lumbar disc surgery Friday at New England Baptist Hospital. They also said they expect him to be ready to return at next season's training camp.
Sullinger left Wednesday's game vs. the Kings in the first quarter because of back spasms. He appeared in 45 games this season and averaged 6.0 points, 5.9 rebounds and 19.8 minutes.
Sullinger's draft stock fell because of concerns over his back when he came out of Ohio State in June, and the Celtics selected him with the 21st pick. The 6-9, 260-pound Sullinger played two seasons at Ohio State.
At the NBA Draft combine, doctors discovered a herniated disc in his back, but Celtics president Danny Ainge said the team felt "comfortable" drafting him.
“We were concerned and we did our research on him and we felt comfortable. But there are some issues there. Our medical staff thinks short term and long term there may be some maintenance issues with the back," Ainge said in June.
“[Coach] Doc Rivers played with a herniated disc for 13 years. So, he may need surgery at some point and may not. All I know is what the MRI results were at the end of the combine in Chicago.”
Yahoo! Sports' Adrian Wojnarowski was first to report the news.