Objective In a prospective study we analysed the frequency of intraoperative capsule rupture among 161 ovarian tumours operated on endoscopically, using total removal of the adnexa with protected retrieval. Subjects and methods Between June 1993 and September 1997 we carried out endoscopic surgery on 161 consecutive patients, presenting with ovarian tumours up to 10 cm in diameter, and assumed to have an increased risk for malignancy on the basis of menopausal status, sonography findings or endoscopic evaluation. The risk of tumour rupture was related to the different phases of the operation (resection and extraction) and to the presence and location of intra‐abdominal adhesions. Results Malignancies were found in 6.83% of the patients. Capsule rupture occurred in 13 cases (8%). There was no instance of malignant cell spillage because of intraoperative capsule rupture. The statistical probability of malignant cell dissemination was 0.55% in our series. During resection, rupture of suspicious but not malignant tumours occurred in six cases (3.7%). The probability of spilling cyst contents was closely associated with the presence and the location of intra‐abdominal adhesions, the highest spillage rate (16.6%) being found in tumours with adhesions to intestine. During extraction, contamination on account of bag rupture occurred in seven cases (4.3%). Conclusion Using adequate endoscopic resection and removal techniques, suspicious ovarian tumours under 10 cm in diameter can be operated on endoscopically with a low risk of tumour rupture.