Klinefelter syndrome [KS] is the most common sex chromosomal disorder in males and historically patients have been labeled as sterile. After the introduction of microdissection testicular sperm extraction [micro-TESE] , successful sperm retrievals for intracytoplasmic sperm injection [ICSI] have been reported. A retrospective study was undertaken on ten patients with non-mosaic KS undergoing micro-TESE for ICSI. The testicular volume and FSH and LH levels of each patient were measured. Karyotypes were confirmed by analyzing peripheral lymphocyte metaphases. Physical examination of the external genitalia was performed in all patients to rule out any co-existing anomaly. Micro-TESE was performed in order to investigate the presence of seminiferous tubules which may contain spermatozoa. When testicular spermatozoa were found in micro-TESE, ICSI was performed. Embryos were evaluated for further development. Fertilization was considered to have occurred after the visualization of the two pro-nuclei stage of the oocyte 24 hours after the intracytoplasmic injection of the motile spermatozoa. Pregnancy was confirmed by visualization of an intrauterine gestational sac under ultrasonographic examination. Testicular biopsy revealed motile spermatozoa in 6 of 9 patients [66.6 %] . Fertilization rate per embryo-transfer was 40%. One patient was able to conceive and fathered a healthy boy weights 3410 g at the 39 [th] week of gestation. Retrieval of testicular spermatozoa by micro-TESE is possible for azoospermic men with KS when assisted reproductive techniques are applied. For patients with KS who want to conceive, assisted reproductive techniques [ART] should be recommended