© 2022 - IOS Press. All rights reserved.BACKGROUND: Semen analysis is a routine predictor of male fertility, and however, measurements of sperm morphology, motility, and concentration do not always evince genomic defects. OBJECTIVE: To investigate sperm parameters of renal transplant patients and to evaluate sperm DNA defects. METHODS: Seminal samples from 25 healthy controls and 56 transplantation patients were analyzed to evaluate DNA fragmentation by TUNEL. The differences in TUNEL-assay results and seminal parameters were compared between kidney transplant patients and controls. RESULTS: Among the azoospermic patients, 37.5% had fathered children before the disease. Three patients receiving sirolimus treatment had oligoasthenoteratozoospermia and infertility. In kidney transplant patients, DNA fragmentation was slightly higher than controls. Total motility (%) of the spermatozoa from the kidney transplant patients (42.2±21.9) was significantly lower (P < 0.05) than those of the control group (64.3±11.9). Moreover, control individuals had significantly higher (P < 0.05) normal morphology (23.2%) compared to the patient group (20.3%). Concerning sirolimus treatment, three patients had severe oligoasthenoteratozoospermia in their ejaculate, and however, DNA fragmentation rates were not significantly higher than those in the remaining individuals of the transplant group. CONCLUSIONS: The sperm DNA fragmentation rate in kidney transplant patients was slightly higher than in the control group (P = 0.09). However, the amount of spermatozoa DNA damage may lead to infertility in kidney transplant patients.