Key PointsQuestionWhat are the use and outcomes of neoadjuvant chemotherapy (NACT) for treatment of less common epithelial ovarian cancer subtypes?FindingsIn this cohort study of 3880 patients in the National Cancer Database with stage III to IV clear cell, low-grade serous, or mucinous ovarian cancers who received multimodal surgery and chemotherapy, NACT use increased in clear cell and low-grade serous carcinomas from 2006 to 2017. Patients with low-grade serous carcinoma who received NACT had lower overall survival rates than those receiving primary surgery, and the Surveillance, Epidemiology, and End Result Program cohort evaluation and meta-analysis supported the results.MeaningThe findings of this study suggest that there is a gradual increase in the number of patients receiving NACT for less common epithelial ovarian cancer in the US; NACT may be associated with poor survival outcomes in low-grade serous carcinomas.