Abstract： Objective To investigate clinicopathological characteristics of recurrent endometriosis and outcomes of secondary surgery.Methods From Jan.2003 to Dec.2008,69 cases with recurrent endometriosis operated by the same senior gynecologist in Peking Union Medical College Hospital were studied retrospectively in order to summarize clinicopathological characteristics and clinical outcomes.In prior surgery,both ovaries were involved in 29 cases (42％,29/69),and unilateral ovarian endometriomas were found in 40 cases ( 58％,40/69),including 19 cases (48％,19/40) with left lesions and 21 cases (52％,21/40) with right lesions.After first surgery,57 cases presented recurrent pelvic cystic masses and 12 cases presented moderate to severe pain without pelvic mass.Results The median recurrence interval was 38 ( 1 - 144) months.Among 57 cases with recurrent pelvic masses,bilateral ovarian endometiomas recurred in 24 cases at median recurrence interval of 31 months.Unilateral ovarian endometrioma recurred in 33 cases at recurrence interval of 39 months.There was no significant different recurrence period between blilateral and unilateral recurrent ovarian mass ( P =0.452).The recurrent rate of left and right side ovarian lesion was 77％ (37/48) and 68％ (34/50 cases),respectively,which did not reach statistical difference (P=0.396).Among 12 recurrent cases with pure pelvic pain,10 cases were founded combined with adenomyosis ( AM),of which 4 cases had deep infiltrated endometriosis (DIE).Compared with the 40 cases of simple ovarian endometriomas,29 cases complicated by DIE and (or) AM had longer operation time (75.1 min vs.49.9 min,P=0.017) and more blood loss (114.9 ml vs.38.4 ml,P＜0.05).In those 69 recurrent endometriosis patients,the median period of following-up was 32 months (3 months to 8 years).Six cases showed recurrent disease again at median recurrence interval of 3 years ( 6 months 6 years).Thirty-eight cases had expecting childbearing,however,only 4 women underwent childbirth.Conclusions The rate of clinical diagnosis of recurrent endometriosis is quite high.Pain is mostly associated with AM.The major difficulty and challenge of secondary surgery was ovarian endometrioma combined with DIE or AM.Prognosis of recurrent endometriosis is not optimistic after secondary surgery.