This study was performed to examine the contribution of genetic polymorphism of oestrogen and androgen receptor (AR) genes in male infertility. We have studied in total 173 Greek men, 109 infertile patients and 64 controls (group A). Patients were divided in to three subgroups: group B (n=29) with idiopathic moderate oligospermia, group C (n=42) with azoospermia or idiopathic severe oligospermia and group D (n=38) with azoospermia or oligospermia of various known aetiologies. All patients and controls were genotyped for two polymorphisms of the oestrogen receptor alpha (ERalpha) gene and also for the (CAG)n repeat length polymorphism of the X-linked androgen receptor (AR)gene. The control group had statistically significant difference from group C regarding the XbaI polymorphism of ERalpha gene. Despite the fact that we did not observe any statistically significant differences in the mean and range of the CAG repeat number, the frequency of the higher repeats of the nucleotide repeat sequence (CAG)n of the AR gene was 2-4 times higher in groups B and C compared with the control group A. Our results indicate that both ERalpha and AR gene play significant role in male fertility. It is possible that a synergy may exist between unfavourable genotypes of these two genes in male infertility.