Abstract Objective To compare the results of removing mature teratoma with laparoscopy or without laparoscopy. Design A prospective, randomised trial. Setting Medical centre. Participants Seventy-nine women with mature teratomas identified using results of ultrasound examinations and biochemical markers. Intervention Cystectomy with laparoscopic approach or without laparoscopic approach through a culdotomy. Methods Patients were randomly assigned to have their cysts removed via vaginal cystectomy without laparoscopy ( n=37, Group A) or laparoscopic cystectomy via culdotomy opening ( n=42, Group B). Inclusion criteria were history of vaginal delivery, no previous abdominal surgery, no history of pelvic inflammatory disease, no medical illness, and no presenting symptoms. Eight women randomised to Group A withdrew before surgery. The laparoscopically resected tumours were each put into a cellulose bag, and tumours without laparoscopic-assistance were removed directly via the vagina. Results Blood loss in Group A (88±37 ml) was significantly more than that in Group B (64±20 ml, P=0.000). The post-operative recovery times were 20 and 17 hours, respectively ( P=0.030). The rates of successful surgery were 58.6 and 97.6%, respectively ( P=0.002). The spillage rates were 44.8% and 19.0%, respectively ( P=0.006). There were no significant differences in tumour size, patient age, and operative time between groups. Conclusion Cystectomy without assistance of laparoscopy could be applied to manage mature teratoma of the ovary; however, because of the difficulty of this technique, we had high percentages of tumour spillage and more blood loss during operation and a high percentage of patients who required conversion to laparotomy compared with laparoscopic cystectomy. We favoured laparoscopically assisted cystectomy to manage mature teratoma.