OBJECTIVE To review the efficacy and safety of unilateral ovariectomy by use of a standing hand-assisted laparoscopic approach and evaluate the effect of ovary size on posttransection hemorrhage after application of a linear stapling device. METHODS Case series. METHODS Horses (n=65) aged 2-20 years. METHODS Medical records of mares that had ovariectomy performed by use of a standing hand-assisted laparoscopic approach were reviewed. Data retrieved were signalment, ovary removed (left, right), ovarian size, ovarian pathology, intraoperative and postoperative complications, and length of hospitalization. RESULTS Mean ovarian diameter was 17 cm. Histopathology (52 mares) confirmed 41 granulosa cell tumors (79%), 8 ovarian cysts (15%), 1 teratoma (2%), and 2 ovaries (4%) without abnormalities. Hemorrhage was observed laparoscopically in 16 mares after transection of the mesovarium. Complications encountered during surgery included 1 mare collapsing in the stocks and 1 mare that hemorrhaged excessively from the incision. Postoperative complications included 2 cases of mild colic. Overall complication rate was 6%. CONCLUSIONS All attempts to remove the target ovary were successful. The approach is safe for the mare, as complications encountered were similar to those recently reported for other approaches.