Objective: To compare COH characteristics and IVF outcomes among IVF-ET patients who were treated with various therapeutic modalities for ovarian endometriomas and to propose effective pre-cyclic therapeutic modalities to improve IVF-ET outcomes in the patients with ovarian endometriomas. Methods: All cases that had undergone IVF-ET after laparoscopy between January 1997 to August 2003 were reviewed. Forty-eight patients with tubal factor were assigned to Group I. Twenty seven, 22 and 38 patients diagnosed as severe pelvic adhesion with ovarian endometriomas by laparoscopy received only medical therapy (Group II), cyst aspiration (Group III), and sclerotherapy (Group IV), respectively. Laparoscopic cystectomy was performed in 20 patients (Group V). Resistance index was measured on day administering hCG. Results: As compared with Group I, in Group II resistance index increased (p<0.05) but number of oocytes, good-quality oocyte ratio (mature and intermediate oocytes/total retrieval oocytes), fertilization rate, and embryo development rate decreased (p<0.05). In Group III fertilization rate and embryo development rate decreased (p<0.05). There was no difference between Group IV and Group I in all parameters except basal FSH which increased (p<0.05). In Group V basal FSH, and resistance increased (p<0.05) and number of oocytes and good-quality oocytes ratio decreased (p<0.05). Conclusion: Sclerotherapy is an effective therapeutic option which can be done prior to IVF-ET cycles in the patients with ovarian endometriomas. Further studies on a large scale are necessary to confirm these data.