ABSTRACT
<p><b>OBJECTIVES</b>To study the correlation and effect of smoking on the semen quality of men.</p><p><b>METHODS</b>61 men, non-smoker, who had one or more children as normal fertility control group and adult males attending the infertility clinic, including 110 non-smokers and 191 smokers, were recruited for the study. The smokers were divided into subgroups according to the amount and duration of smoking. Semen parameters(volume, sperm density, viability, motility and morphology) were examined and seminal plasma contents of Zn, Cu and superoxide dismutase (SOD) were determined.</p><p><b>RESULTS</b>The semen volume, pH, sperm density, viability and forward progression, as well as the seminal plasma contents of Zn, Cu and SOD were much lower in the medium, heavy and long-term smokers than in the non-smokers(P < 0.01). The sperm density, viability and forward progression, and the seminal plasma Zn, Cu and SOD levels were negatively correlation with the amount and duration of cigarette smoking(P < 0.001).</p><p><b>CONCLUSIONS</b>The effect of smoking on semen parameters of infertile men were dose-effect and time-effect relationship. Medium, heavy and long-term smoking adversely affected the semen quality in a population of men visiting the infertility clinic.</p>