Background: Semen quality is a measure of the ability of semen to accomplish fertilization. Semen quality involves both sperm quantity and quality. The general population is exposed to metals at low concentrations either voluntarily through supplementation or involuntarily through intake of contaminated food and water or contact with contaminated soil, dust, or air. Some metals, such as lead (Pb), are nonessential xenobiotics that can be measured in most of the general population. Objectives: Our goal in this study is to assess relationships between exposure to lead at environmental levels and human semen-quality parameters. Materials and Methods: The study populations consist of 81 infertile male of general population who are occupationally unexposed to lead and another 26 healthy fertile male as control group. Blood lead and seminal plasma lead measurements performed by the electrothermal-atomic absorption spectrometry (AAS) method. Macroscopic and microscopic examination of semen performed according to WHO recommendations. Seminal plasma separated from the spermatozoa by centrifugation and stored at -20°C until required for analyses. Results: This study showed significant increase in seminal plasma lead mean value in moderate and severe oligozoospermic infertile males than in fertile male controls( p<0.05). The result also showed no statistically significant difference in blood lead concentration among the infertile group compared to fertile controls. Conclusions: The results of this study indicate that even moderate exposure to Pb at environmental level (blood Pb < 400 µg/L) can significantly reduce reproductive capacity in men.