Based on association studies, an increasing number of gene polymorphisms have been proposed as modulators of spermatogenesis. Interestingly, a clear cause-effect relationship between a polymorphism of the POLG gene and oligo(astheno)zoospermia was recently described. The POLG gene contains a polymorphic CAG repeat, and the presence of a homozygous mutant (not10/not10 CAG) genotype was found only in infertile men. In the present study, a large number of infertile patients and normospermic men of Italian origin were studied to define the effect of POLG genotypes on spermatogenic potential and whether the homozygous mutant is specific for spermatogenic disturbances. The mutated genotype was found at the same frequency in both infertile and normospermic men. Mean values of sperm parameters such as sperm count, motility, and morphology did not differ significantly between carriers of the three different genotypes. Our study failed to confirm any influence of the POLG gene polymorphism on the efficiency of the spermatogenesis. More importantly, considering that the homozygous mutant genotype has been found in normospermic fertile men, the analysis of the CAG repeat tract of the POLG gene does not appear to have any clinical diagnostic value.