Background: The purpose of this study was to assess the vasopressin effect on operation time and the need for electrocauterization frequency and ovarian reserve during laparoscopic stripping of ovarian endometriomas. Methods: This was a randomized prospective clinical trial, in which twenty patients between 18-35 years with unilateral endometriomas were randomly divided in two groups of cases and controls. Laparoscopic cystectomy was performed by hydrodissection and stripping method in both groups with diluted vasopressin injected in cases, in comparison to only saline injection in controls. Ovarian hemostasis was achieved by bipolar electrocoagulation. The operation time and frequency of electrocoagulation were compared between two groups. The ovarian reserve was determined by ultrasound examination and laboratory assessment one month before and two months after surgery in two groups. Non parametric data was analyzed by Mann-Whitney test. The p-value less than 0.05 was considered statistically significant. Results: The operation time was less in cases than control group, but the difference was not statistically significant (p=0.065). The frequency of electrocoagulation for hemostasis was less in cases than controls but this difference was not statistically significant (p=0.132). The antral follicle count decreased in both groups two months later, while no significant difference was found between two groups. Conclusion: This study shows that diluted vasopressin decreases operation time and electrocauterization frequency during laparoscopic stripping of ovarian endometriomas; however, the difference between case and control group is not statistically significant.