The general infertility rate is approximately 10 percent in Vietnam whereas male infertility counts for half of it. 10 percent of infertile men are diagnosed with the absence of sperm in the semen (azoospermia). Sertoli cells playa major role in the development of healthy sperms. Researchers have known for many years that the Sertoli cell, the supporting element in the testis, regulates germ cell renewal and differentiation. Hence, research on structural changes, especially on the ultrastructure of rtoli cells of azoospermic patients is essential for an improved diagnosis and treatment of infertile couples. Comparing sertolicells extracted from patients without epididymal spermatozoa (group I) with cells of patients with epididymal spermatozoa (group II) showed differentiation in ultrastructure between the group I and group II. Sertolicells extracted patients in group II have a typically shaped nucleus and are close to that of healthy patients in their general morphology. However, the Sertoli Cells extracted from patients without epididymal spermatozoa have significantly smaller nuclei and an immature cytoplasm.