Choline is a crucial factor in the regulation of sperm membrane structure and fluidity, and this nutrient plays an important role in the maturation and fertilizing capacity of spermatozoa. Transcripts of phosphatidylethanolamine N-methyltransferase (PEMT) and choline dehydrogenase (CHDH), two basic enzymes of choline metabolism, have been observed in the human testis, demonstrating their gene expression in this tissue. In the present study, we explored the contribution of the PEMT and CHDH gene variants to sperm parameters. Two hundred oligospermic and 250 normozoospermic men were recruited. DNA was extracted from the spermatozoa, and the PEMT 2774G.C and CHDH 1432G.T polymorphisms were genotyped. The genotype distribution of the PEMT 2774G.C polymorphism did not differ between oligospermic and normozoospermic men. In contrast, in the case of the CHDH 1432G.T polymorphism, oligospermic men presented the CHDH 432G/G genotype more frequently than normozoospermic men (62% vs. 42%, P,0.001). The PEMT 774G/G genotype was associated with a higher sperm concentration compared to the PEMT 774G/C and 774C/C genotypes in oligospermic men (12.565.6310 6 spermatozoa ml 21 vs. 8.365.2310 6 spermatozoa ml 21 , P,0.002) and normozoospermic men (81.5655.6310 6 vs. 68.1644.5310 6 spermatozoa ml 21 , P,0.006). In addition, the CHDH 432G/G genotype was associated with higher sperm concentration compared to CHDH 432G/T and 432T/T genotypes in oligospermic (11.865.1310 6 vs. 7.865.3310 6 spermatozoa ml 21 , P,0.003) and normozoospermic men (98.6662.2310 6 vs. 58.8633.6310 6 spermatozoa ml 21 , P,0.001). In our series, the PEMT 2774G.C and CHDH 1432G.T polymorphisms were associated with sperm concentration. This finding suggests a possible influence of these genes on sperm quality.