Objective: To determine the optimal effective dose pituitrin in laparoscopic myomectomy for uterine leiomyoma. Design: Prospective, double-blinded, randomized controlled trial. Setting: A tertiary women’s hospital in China. Population: A total of 118 women who underwent laparoscopic myomectomy. Methods: Women were randomly divided into four groups to receive 0, 2, 4, or 6 units of pituitrin in the leiomyoma (groups 0U, 2U, 4U, and 6U, respectively). Main outcome measures: Rate of satisfactory surgical field, hemodynamic changes, total surgical time and blood loss were recorded. Results: The rate of sastisfactory surgical field was 6.7%, 72.4%, 89.7% and 93.3% in groups 0U, 2U, 4U, and 6U, respectively; it was higher in groups 2U, 4U, and 6U than group 0U, but there were no significant differences among the groups 2U, 4U, and 6U. The blood loss was higher in group 0U than that in groups 2U, 4U, and 6U (). Pituitrin was associated with a transient decrease in blood pressures and increase in heart rate in a dose-dependent fashion, with more pronounced changes in groups 4U and 6U and these groups also required higher amount of vasoactive drug to correct hemodynamic changes (p<0.05). Conclusions: Use low-dose pituitrin (2 units) provides a satisfactory surgical field with minimal hemodynamic changes.