OBJECTIVE: To evaluate use of the Harmonic Scalpel (Ethicon Endo-Surgery Inc., Cincinnati, OH) for performing laparoscopic bilateral ovariectomy in standing horses. STUDY DESIGN: Experimental study. ANIMALS: Eight mares aged 2-20 years and weighing 410-540 kg. METHODS: Standing laparoscopic bilateral ovariectomy was performed in 8 mares with normal reproductive tract anatomy. The Harmonic Scalpel (an ultrasonically activated instrument) was used to simultaneously transect and obtain hemostasis of the ovarian pedicle. Necropsy was performed on 4 mares 3 days after surgery and 4 mares 30 days after surgery. Gross and histopathologic evaluation of the ovarian pedicles was performed to characterize tissue reaction. RESULTS: Complete hemostasis of the ovarian pedicles was obtained in all mares. Median transection time for the ovarian pedicle was 28 minutes. Postoperative complications included transient fever, moderate subcutaneous emphysema, and incisional seroma formation. On necropsy examination, there were no signs of generalized peritonitis, postoperative hemorrhage, or adhesion formation. Mild to moderate acute inflammation and scar formation with moderate chronic inflammation at the ovarian pedicle was found at 3 and 30 days. Median depth of coagulation necrosis at 3 days was 2.87 mm. CONCLUSIONS: The Harmonic Scalpel appears to provide reliable hemostasis of the ovarian pedicle during elective laparoscopic ovariectomy in horses. Clinical Relevance-The Harmonic Scalpel represents a safe alternative to other methods of hemostasis during elective laparoscopic ovariectomy in horses.