Glutathione S-transferases (GSTs), superoxide dismutase 2 (SOD2) and NAD(P)H:quinone oxidoreductase 1 (NQO1) are anti-oxidant enzyme genes. Polymorphisms of GSTs, SOD2 and NQO1 have been reported to influence individual susceptibility to various diseases. In an earlier study, we obtained preliminary findings that a subset of glutathione S-transferase T1 (GSTT1)-wt patients with varicocele may exhibit good response to varicocelectomy. In this study, we extended the earlier study to determine the distribution of genotype of each gene in the infertile population and to evaluate whether polymorphism of these genes affects the results of surgical treatment of varicocele. We analyzed 72 infertile varicocele patients, 202 infertile patients without varicocele and 101 male controls. Genotypes of GSTs were determined by polymerase chain reaction (PCR). Genotyping of SOD2 and NQO1 was performed using the PCR-restriction fragment length polymorphism (PCR-RFLP) method. A significantly better response to varicocelectomy was found in patients with the GSTT1-wt genotype (63.2%) and NQO1-Ser/Ser genotype (80.0%) than in those with GSTT1-null genotype (35.3%) and NQO1-Pro/Pro or NQO1-Pro/Ser genotype (45.2%), respectively. The frequencies of glutathione S-transferase M1/T1, SOD2 and NQO1 genotypes did not differ significantly among the varicocele patients, idiopathic infertile patients and male controls. GSTT1 genotype is associated with improvement of semen parameters after varicocelectomy. As the number of patients with NQO1-Ser/Ser genotype was not sufficient to reach definite conclusions, the association of NQO1 genotype with varicocelectomy requires further investigation.