Background: The aim of this study was to compare the effects of LigaSure™ versus conventional bipolar techniques on operating time and blood loss during laparoscopic salpingo-oophorectomy in a randomized controlled trial. Methods: In three teaching hospitals, 100 women undergoing a laparoscopic salpingo-oophorectomy were randomized for LigaSure or conventional bipolar instruments. Primary outcome was operating time (from initial skin incision to removal of the specimen). Secondary outcome measures were total operating time (from initial skin incision to skin closure), time to dissect the ovarian and infundibulopelvic ligaments, intraoperative blood loss, and subjective judgment of the instrument used. Results: There were no differences in operating time and total operating time using LigaSure versus conventional bipolar instruments: 41.0 vs. 39.2 min (p = 0.78; 95 % CI = -10.9 to 14.5) and 54.6 vs. 58.6 min (p = 0.46; 95 % CI = -14.8 to 6.8), respectively. The mean blood loss using LigaSure versus conventional bipolar instruments was 38 vs. 33 mL (p = 0.73; 95 % CI = -22.7 to 32.2). Various subjective efficacy and instrument handling parameters of the two instruments varied among participating centers. Conclusion: There were no significant differences in operating time and blood loss with the use of LigaSure compared to conventional bipolar instruments during laparoscopic salpingo-oophorectomy, even after correction for potential confounders. © The Author(s) 2012.