Abstract Study question Is GSTM1 polymorphism a putative biomarker of male infertility. Is there a possible correlation between GSTM1 presence, oxidative stress and male infertility? Summary answer A possible correlation may be established between GSTM1 polymorphism, and sperm mobility and morphology. Additionally oxidative potential may also be associated with fertility. What is known already Approximately 7% of men worldwide are affected by male infertility, which contributes to 40–50% of all infertility cases. Basic sperm analysis remains the main procedure of diagnosing male infertility, although there is still doubt whether it provides accurate clinical outcomes More accurate tests are essential for the diagnosis of male infertility. Oxidative stress is involved in the etiology of male infertility, with 30% to 80% of infertile men having increased levels of sperm free radicals. Recent research has shown that oxidative stress when combined with GSTM1-null genotype negatively affected the sperm quality of infertility group compared to the control group. Study design, size, duration Ninety semen samples were collected and divided into 2 groups. The study group consisted of sperm samples from 51 men identified as infertile according to WHO guidelines(case group).Sperm samples from 39 men with normal sperm count parameters (control group) were used for the control group. Participants/materials, setting, methods For all samples a sperm diagram was performed. and DNA was extracted. Polymerase chain reaction with specific for GSTM1 gene primers followed by agarose electrophoresis was applied to detect the presence of polymorphism. The MiOXSYS method was used to detect the oxidative potential. Main results and the role of chance This study shows that in the control group the presence of polymorphism was associated with a reduced number of immobile sperm cells (p = 0,035) while it appears to affect the normal morphology of the sperm(p = 0,042). In the infertility group the presence of the gene was significantly correlated with age(p = 0.046). No statistically significant difference was observed for the presence of the polymorphism between the 2 groups.In addition, we investigated the effect of oxidative potential with the MiOXSYS system and its relationship with sperm parameters. It was found that the two groups differed significantly when measuring oxidative potential, and that oxidoreduction potential affects sperm concentration/ml, total sperm count, type B motility and viscosity in the infertile male group. Limitations, reasons for caution A larger sample size could increase the accuracy of the results. Wider implications of the findings: Studying the relation of the oxidative stress with sperm parameters may lead to the establishment of a genetic profile of increased risk of infertility, which would be of major importance especially in cases of idiopathic infertility. Trial registration number Not applicable