Purpose: To compare the outcome of intracytoplasmic sperm injection (ICSI) cycles performed with frozen-thawed epididymal spermatozoa between patients who respond poorly and patients who respond well to ovarian stimulation Methods: 17 patients suffering from obstructive azoospermia underwent microsurgical retrieval of epididymal spermatozoa (MESA) and the spermatozoa were frozen. The frozen-thawed spermatozoa were used in subsequent ICSI cycles. In six patients, the female partners responded poorly to ovarian stimulation. They accomplished nine ICSI cycles. In 11 patients, the female part­ners responded well to ovarian stimulation and they accomplished 16 cycles.

Results: Poor responders were older than those who reponded well. The mean number of metaphase II oocytes collected was lower in the poor responder group. In the poor responders, two couples failed to fertilise the oocytes in two ICSI cycles. In the good responders, one couple failed to fertilise the oocytes in an ICSI cycle. There were no significant differences in fertilization rates between the two groups. The estradiol concentrations on the day of HCG administration were significantly higher in the good respon­ders. There was no pregnancy in the poor responder group, while three patients who responded well conceived. Eight good respon­ders had 34 supernumerary 2PN oocytes which were cryopreserved. Conclusion: Frozen-thawed epididymal spermatozoa from men with obstructive azoospermia are potent to achieve satisfactory fertilization rates. Poor ovarian response to stimulation induction appears to be the main limiting factor in reaching the stage of transfer It is preferable in older women to cannel circles with poor response in the hole that a better response might be obtained in a: subsequent cycle. Thus, the frozen-thawed epididymal sperm can be preserved and the most stressful and expensivephase of IVF-ICSI treatment can be avoided.