To investigate whether aspiration o f ovarian endometriomas before controlled ovarian stimulation(COH)improves in-tracytoplasmic sperm injection(ICSI )outcomes.Prospec-tive study.University hospital.A p rospective analysis of171patients with ovarian endometriosis and tubal factor infertility were divided into four g roups:aspiration of en-dometriomas at the beginning of COH i n patients with o-varian endometriomas and no history of previous surgery(n =41)(group 1);nonaspirated endometriomas(n =40)(group 2);history of ovarian surgery for endometriomas in patients without ovarian endometriomas at the beginning of COH(n =44)(group 3);and tubal factor infertility(n =46)(control group 4).Aspiration of endometriomas.Clinical parameters,characteristics of COH,and ICSI re-sults were analyzed.We observed hig her levels of E2on the day of hCGinjection after aspira tion of endometriomas compared with nonaspirated endometriomas.When we compared all endometriomas and tubal factor(control)groups,we observed a lower number of total follicles(>17mm)and metaphase II(MII)oocytes in nonaspi-rated and resected endometrioma gro ups and a longer du-ration of COH in the nonaspirated end ometrioma group compared with the tubal factor group.Implantation and clinical pregnancy rates were simil ar among all groups.In the current study,all patients with endometriomas had significantly lower numbers of MII o ocytes compared with those in patients with tubal factor i nfertility.We propose that aspiration of endometriomas before COH neither re-duces the amount of gonadotropins nor increases the num-ber of follicles >17mm,the number of MII oocytes re-trieved,the implantation rates,or the clinical pregnancy rates.Resection of small endometriomas(1-6cm)may not present any additional benefits to the IVF -ICSI cycle outcomes. To investigate whether aspiration of ovarian endometriomas before controlled ovarian stimulation (COH) improves in-tracytoplasmic sperm injection (ICSI) outcomes.Prospec-tive study. University hospital. Apparent perspectives of 171 patients with ovarian endometriosis and tubal factor infertility were divided into four g roups: aspiration of en-dometriomas at the beginning of COH in patients with o-varian endometriomas and no history of previous surgery (n = 41) (group 1); nonaspirated endometriomas (n = 40) (group 2) surgery for endometriomas in patients without ovarian endometriomas at the beginning of COH (n = 44) (group 3); and tubal factor infertility (n = 46) (control group 4). Aspiration of endometriomas. Clinical parameters, characteristics of COH, and ICSI re-sults were analyzed. We observed hig her levels of E2on the day of hCGinjection after aspira tion of endometriomas compared with nonaspirated endometriomas. WHhen we compared all endometriomas and tubal factor (control) groups, we observed a lower number of total follicles (> 17 mm) and metaphase II (MII) oocytes in nonaspi-rated and resected endometrioma gro ups and a longer du-ration of COH in the nonaspirated end ometrioma group compared with the tubal factor group. Implantation and clinical pregnancy rates were simil ar among all groups. the current study, all patients with endometriomas had significantly lower lower numbers of MII o ocytes compared with those in in with tubal factor i nfertility. We propose that aspiration of endometriomas before COH neither re-duces the amount of gonadotropins nor increases the num-ber of follicles> 17 mm, the number of MII oocytes re-trieved, the implantation rates, or the clinical pregnancy rates. Review of small endometriomas (1-6 cm) may not present any additional benefits to the IVF -ICSI cycle outcomes.