Introduction: GSTM and GSTT are subclasses of glutathione s-transferase that is present on human sperm surface and plays an important role against oxidative stress. This study aimed to investigate the polymorphisms of GSTT1 and GSTM1 in regard to sperm parameters. Methods: This case-control study involved 46 men with varicocele and 48 men without varicocele. Semen analyses were carried out according to WHO guidelines. Blood DNA was extracted using salting out procedures. Polymorphism of GSTT1 and GSTM1 genes was determined trough multiplex-PCR respectively. Results: Frequencies of GSTM1 null genotype in men with varicocelc and men without varicocele groups were 60.9 and 41.7 respectively. There were no statistically significant differences between Gstm1 null and positive genotype in two groups (p>0.05). Frequencies of gstt1 null genotype in case and control groups were 47.8 and 50 respectively. There were no statistically significant relationship between gstt1 null and positive genotype in two groups (p>0.05). Conclusions: Deficiency of enzyme activity in gstm1 null genotype did not affect morphology as well as slow and quick progressive of sperm but caused the significant decrease in count of sperm between gstm1 null and positive genotype. In the case of gstt1, gstt1 null genotype did not affect sperm parameters that may be related to compensate activity of other genes in this super family.