The aim of the study was to summarize our five years experience (1996-2000) of testicular spermatozoa for intracytoplasmic sperm injection in Hungary. The influence of sperm count, maternal age, number of transferred embryos, and application of assisted hatching on outcome was investigated. Testicular spermatozoa were retrieved by microsurgical testicular sperm extraction. Samples were classified depending on the number of spermatozoa. Indication for testicular sperm extraction in conjunction with intracytoplasmic sperm injection was severe azoospermia or azoospermia combined with tubal origin infertility. Ovarian stimulation was carried out using an ultrashort protocol with GnRH agonist and gonadotrophin. Intracytoplasmic sperm injection was performed without PVP. Embryos were cultured for 48 or 72 h before embryo transfer. Indications for assisted hatching included elevated maternal age, increased zona thickness or at least two previous unsuccessful IVF cycles. Testicular spermatozoa were successfully retrieved in 218 out of 273 cases. Extreme low sperm count was found more frequently in cases of nonobstructive azoospermia. No significant differences were observed in fertilization rate (61.1% vs. 51.7%) or clinical pregnancy rate (29.0% vs. 26.7%) between patients with obstructive or nonobstructive azoospermia. Maternal age, number of transferred embryos and application of assisted hatching had a significant effect on outcome. A total of 55 clinical pregnancies were achieved, including 14 sets of twins, three sets of triplets and two sets of quadruplets. It is concluded that testicular sperm extraction is an efficient way of obtaining testicular spermatozoa, allowing not only successful fertilization by ICSI, but also freezing of testicular spermatozoa for use in subsequent cycles.