To assess the effects of oral contraceptive pills (OCPs) for endometriosis in women after conservative surgery, we performed a search of PubMed, Embase, ISI Web of Science, Cochrane Library, Scidirect, Chinese VIP, CNKI and WANGFANG database. Randomized controlled trials (RCTs) of OCPs in postoperative medical therapy for endometriosis were collected. Articles published as of January 2013 with no language restriction were identified using defined keywords, and 15 studies comprising 1850 patients were included. There was a significantly higher rate of total endometriosis remission [OR = 2.55, 95% CI (1.68, 3.86), p < 0.00001] and a lower rate of recurrence [OR = 0.31, 95% CI (0.22, 0.45), p < 0.00001] in the OCPs group compared with surgery alone. There appears to be no statistical difference in pregnancy rates between the OCPs group as compared with surgery alone or other hormonal drug treatments in infertility patients. As for the rate of recurrence and complete remission, there were no statistical differences among OCPs and gestrinone, mifepristone or GnRH-a groups. However, OCPs users had less side effects that were more mild as compared with patients using other hormonal treatments.