Reduced sperm quantity and motility are primary causes of infertility in men. Before researchers showed that, Nsun7 gene has roles in sperm motility of mouse, that creation defect in this gene is cause infertility. This gene in human located in chromosome 4, with 12 exons and a hot spot exon (exon7). Our aim is study of the mutations of the exon7 in the normospermic and asthenoteratospermic men. For this, 30 semen samples including fertile and asthenoteratospermic men were collected from IVF center. Semen analysis was performed according to WHO guidelines. A Phenol-chloroform method was used for total DNA extraction from sperm. The exons 7 amplified by forward primer Sun7-F: 5’-GACAAATCTCGAAGTCTTGCTG; and reverse primer Sun7-R: 5’-ACATCCTATTTTTGTGAAAAGGGT. The PCR products direct sequenced and analyzed for mutations. Analyses of PCR direct sequences showed transition mutation (C26232T) in asthenoteratospermic men. This mutation doesn't see in fertile men. We probably that, low semen parameters of the asthenoteratospermic men can be close correlate with these mutations. Thus, analyses of exon 7 direct sequence candidate as a one of diagnosis genetic markers of infertility.