Background: The dilation and torsion of testicular veins in the plexus pampiniformis causes Varicocele, which is asurgically repairable cause of male infertility. This study assessed the impact of varicocelectomy on semen characteristics,total motile sperm count (TMSC) and sperm DNA integrity in patients with severe oligoasthenoteratozoospermia(OAT).Materials and Methods: In this prospective study, semen samples of 360 men with severe OAT who underwentvaricocelectomy according to World Health Organization (WHO) criteria 2021 were studied (pre-operatively and at 6,12, and 18 months post-operatively).Results: The average age of our patients was 38.5 years. The mean spermatozoa concentration was found to be 1.60 ±0.83 million/ml pre-operatively, while the mean post-operative concentration was 5.17 ± 1.23 million/ml at 6 months,8.32 ± 0.98 million/ml at 12 months, and 13.51 ± 1.48 million/ml at 18 months (P