Objective To compare the effects of LigaSure versus the conventional bipolar technique on operating time and blood loss during laparoscopic hysterectomy.Design A randomised controlled trial.Setting Three teaching hospitals.Population Women undergoing a laparoscopic hysterectomy for benign indications.Methods 140 women undergoing a laparoscopic hysterectomy were randomised for LigaSure or conventional bipolar instruments.Main outcome measures Primary outcome was operating time from initial skin incision till detachment of the uterus. Secondary outcome measures were total operating time (from initial skin incision till final skin closure), time to dissect the adnexal ligaments, intra-operative blood loss and subjective evaluation by the surgeon of the instrument used.Results No differences in operating time (from initial skin incision till uterine detachment and initial skin incision till final skin closure) using LigaSure versus conventional bipolar instruments: 97.6 versus 91.8 minutes (P = 0.39, 95% CI -7.6 to 19.2), and 148.1 versus 142.1 minutes (P = 0.46, 95% CI -10.1 to 22.3), respectively. The mean blood loss using LigaSure versus conventional bipolar was 234.1 versus 273.1 ml (P = 0.46, 95% CI -39.1 to 52.7). Various subjective efficacy and instrument handling parameters were significantly different between the two instruments and between the different participating centres.Conclusions There were no significant differences in operating time and blood loss between the use of LigaSure and the use of conventional bipolar instruments during laparoscopic hysterectomy, even after correction for potential confounders. User satisfaction parameters were assessed as significantly different by surgeons of the participating centres.