Dermoid cysts are usually treated by ovarian cystectomy or oophorectomy. Less invasive laparoscopic treatment of dermoid cysts has replaced traditional laparotomy as the preferred surgical approach, but has been associated with a greater likelihood of accidental cyst rupture, intraperitoneal spillage of contents, and subsequent granulomatous (chemical) peritonitis. In the early 1990s, the use of an endoscopic retrieval bag placed under the cyst during surgery was introduced to minimize spillage into the peritoneal cavity. This retrospective study investigated whether use of the endoscopic bag among a population of patients undergoing laparoscopic surgery for ovarian dermoid cysts could prevent intraperitoneal spillage of cyst contents and postoperative granulomatous peritonitis. The study was conducted between 1982 and 2003 in 314 women with ovarian dermatoid cysts confirmed by histology as benign cystic teratomas. Data were analyzed from 2 groups of women: group 1 was comprised of 174 patients in whom endoscopic bags were not used (1983-1992), and group 2 consisted of 140 patients in whom endoscopic bags were used (1992-2003). The primary study endpoints were the incidence of cyst rupture with intraperitoneal spillage of contents and rate of postoperative granulomatous peritonitis in each group. Routine use of the bag during laparoscopy reduced the frequency of accidental cyst rupture compared to a total laparoscopic approach (group 1, no bag: 26/174 or 15% versus group 2, bag: 39/140 or 28%; P = 0.005). In group 1, the incidence of granulomatous peritonitis after intraperitoneal spillage was 8% (2/26). No cases of granulomatous peritonitis were reported in group 2. These findings demonstrate that routine use of an endoscopic retrieval bag during laparoscopic removal of ovarian dermoid cysts can minimize the risk of granulomatous peritonitis.