Spermatogenesis is the most important stage in male fertility. In the present study, many factors affecting spermatogenesis were evaluated in seminal plasma and homogenates of sperms from fertile and infertile males. The levels of some heavy metals, malondialdehyde (MDA) and reduced glutathione (GSH) as well as superoxide dismutase (SOD) activity were measured in both seminal plasma and homogenate supernatant of sperm from fertile and infertile males. Two hundred and sixteen human semen samples were collected and divided into five groups: group I (GI) included 70 semen samples as the control, and four infertile groups (GII - GV) according to WHO criteria. The levels of Fe2+, Cd2+ and MDA in seminal plasma and sperm homogenate supernatant of infertile groups were highly and significantly increased compared to their levels in control. However, GSH level and SOD activity in seminal plasma and sperm homogenate supernatant of infertile men were highly and significantly decreased compared to the control. In conclusion, the levels of heavy metals and oxidative stress were associated with human male spermatogenesis dysfunction and might be useful tools in predicting sperm density.