RESUMEN
<p><b>AIM</b>To investigate the changes of the spermatozoa ultrastructures before and after renal transplantation in uremic patients.</p><p><b>METHODS</b>The sperm of five uremic patients before and after transplantation and four healthy volunteers were collected and examined by scanning electron microscopy.</p><p><b>RESULTS</b>Abnormal spermatozoa were found in patients pre-transplantation; abnormalities included deletion of the acrosome, absence of the postacrosomal and postnuclear ring, dumbbell-like changes of the head, tail curling, and absence of the mitochondrial sheath in the mid-segment. After renal transplantation, most of the spermatozoa became normal.</p><p><b>CONCLUSION</b>There are many abnormalities with regard to the appearance and structure of the head, acrosome, mitochondria and tail of the spermatozoa in uremic patients. The majority of the spermatozoa returned to normal after renal transplantation, but a few still presented some abnormalities possibly relating to the administration of immunosuppressants.</p>