To explore the associations among semen quality, oxidative DNA damage in human spermatozoa and concentrations of cadmium, lead and selenium in seminal plasma, 56 non-smoking subjects were asked to collect semen by masturbation into a sterile wide-mouth metal-free plastic container after 3 days of abstinence. The conventional semen parameters were analysed. The concentrations of Cd, Pb and Se in seminal plasma were detected using atomic absorption spectrophotometer. 8-OHdG levels in sperm DNA were measured using HPLC-EC. The results showed that the geometric mean concentrations of Cd, Pb and Se were 0.78, 7.8 and 51.4 microg/l, respectively. The geometric mean of 8-OHdG/10(6) dG was 51.4 (95% CI: 21.5-123.0). A significant inverse correlation exists between Cd and sperm density (r=-0.28, P<0.05), and between Cd and sperm number per ejaculum (r=-0.27, P<0.05). In contrast, there was a significantly positive correlation between Se and sperm density (r=0.50, P<0.01), between Se and sperm number (r=0.49, P<0.01), between Se and sperm motility (r=0.40, P<0.01), and between Se and sperm viability (r=0.38, P<0.01). No statistically significant correlation was observed between Pb and semen quality. A significant inverse correlation was observed between 8-OHdG and sperm density (r=-0.34, P<0.01), between 8-OHdG and sperm number per ejaculum (r=-0.30, P<0.01), and 8-OHdG and sperm viability (r=-0.24, P<0.05). 8-OHdG was significantly correlated with Cd in seminal plasma (r=0.55, P<0.01). A significant but weak positive correlation was found between 8-OHdG and Pb concentration in seminal plasma (r=0.28, P<0.05). In contract, a significant inverse correlation was observed between 8-OHdG and Se concentration in seminal plasma (r=-0.40, P<0.01). The results indicate that Cd in seminal plasma could affect semen quality and oxidative DNA damage in human spermatozoa. Se could protect against oxidative DNA damage in human sperm cells. Pb did not appear to have any association with the semen quality when concentration of Pb in seminal plasma was below 10 microg/l.