To determine the prevalence of high levels of sperm DNA damage among infertile men with normal and abnormal semen parameters, 90 patients were subdivided into the following three groups. Group A (n = 30): men with normal semen parameters who acted as the controls. Group B (n = 30): asthenozoospermic men and group C (n = 30): teratozoospermic men, suffering from male infertility. DNA damage was evaluated by the rate of DNA fragmentation index (DFI) as assessed by the terminal desoxynucleotidyl transferase-mediated dUTP nick-end labelling assay. It was found that the difference was not significant between the percentage of DFI in patients with asthenozoospermia and the normospermic men (9.46% +/- 8.68 and 8.19 +/- 6.84 respectively, P-value not significant). The patients with teratozoospermia showed a significantly higher percentage of DNA fragmentation compared with the controls (respectively 21.37 +/- 17.26% and 8.19 +/- 6.84%, P < 0.001). There was a positive correlation between abnormal sperm morphology and the DFI (r = 0.44, P < 0.01) in group C. It is concluded that the impairments of sperm parameters were associated with an increase of DNA fragmentation; this association was strictly related to atypical forms.