Extrauterine choriocarcinoma is a rare form of gestational trophoblastic tumor. Extrauterine choriocarcinoma of the greater omentum is extremely rare in the literature. A 24-year-old female with irregular vaginal bleeding, mimicking as ectopic pregnancy, underwent emergency exploratory laparotomy and local excision of the greater omentum mass. The serum beta-human chorionic gonadotropin level decreased rapidly after operation; however, it rose up again before long. Pathology showed choriocarcinoma in the greater omentum. No evidence showed lesions on uterus. No other metastasis was found. Multiple courses of combined chemotherapy were effective for this case. Surgical excision and combined chemotherapy were effective for extrauterine choriocarcinoma of the greater omentum.