Study ObjectiveTo compare the incidence of unsuspected uterine sarcoma based on surgical approach, open versus minimally invasive, for myomectomy and hysterectomy. DesignRetrospective chart review of demographic data, preoperative characteristics, operative details, and pathology results from the electronic medical record (Canadian Task Force classification II-3). SettingA large, urban, academic medical center. PatientsAll women undergoing myomectomy or hysterectomy performed for a benign indication via a benign gynecologic surgical procedure between 2010 and 2014. Measurements and Main ResultsA total of 1959 myomectomies and hysterectomies were performed, among which 4 unsuspected uterine sarcomas were identified, for an incidence of 2.0 per 1000 cases. The incidence of sarcoma was similar in patients undergoing open abdominal surgery and those undergoing minimally invasive surgery (MIS) (3 in 743 [0.40%] vs. 1 in 1216 [0.08%]; p = .16). The mean age, body mass index, and specimen weights were also similar in the 2 groups. Although more than one-quarter of all cases involved morcellation, the majority via power morcellation, no specimens with sarcoma were morcellated. ConclusionThe incidence of unsuspected uterine sarcoma during myomectomy or hysterectomy for benign indications is low at our institution, and is similar for open and MIS cases. Patients should be counseled on the risks and benefits of both open surgery and MIS approaches.