Serum and seminal plasma cadmium (Cd) concentrations were estimated by atomic absorption spectrophotometry in 60 infertile adult male Nigerians (40 oligozoospermics and 20 azoospermics). The results were compared with Cd level in 40 normozoospermic subjects (matched age, with proven evidence of fertility). The relationship between Cd levels and spermatograms or the hypothalamic-pituitary-gonadal (HPG) -axis was investigated by correlating serum and seminal plasma Cd levels with semen characteristics and hormone levels. The seminal plasma Cd level was significantly higher than those of serum in all studied groups (p<0.001). The serum and seminal plasma Cd levels were increased (p<0.001) in azoospermics in comparison to oligozoospermic and control subjects. A significant negative correlation was observed between serum Cd level and all examined biophysical semen characteristics except sperm volume. A positive correlation was also observed between seminal plasma Cd and FSH. Results of the study for the first time implicate cadmium as a cause of infertility in male Nigerians as well as extend and support previous findings concerning cadmium toxicity and male infertility. The strong deleterious effect of cadmium on spermatogenesis may be due to the systemic and cellular toxicity. A possible relationship between this element and the HPG axis is also suggested.