Abstract: Objective To investigate the effects of computer electromagnetic radiation on reactive oxygen species (ROS)level in semen and sperm fertilization capacity of male adult. Methods Totally 56 male adults were divided into two groups according to their active computer use:control group(without computer use)and exposure group(with computer use of 2 hours per day).The routine parameters of ROS level in semen,sperm acrosin activity,and the rate of sperm penetration of zona-free hamster egg(SPA)were detected according to WHO standards. Results The results showed an increase in ROS level in semen(24.2±17.1 vs 12.2±8.1)and decreases in sperm acrosin activity(78.9±19.8 vs 110.3±23.3) and the rate of sperm penetration of zona-free hamster egg(24.2±17.1 vs 47±19.6)in exposure group compared with those of the control(P<0.05 for all).The comparisons of mean semen volume,pH,sperm motility and viability between exposure and the control group showed no significant difference(P>0.05 for all).But the rate of sperm normal morphology was significantly different(P<0.05). Conclusion The results suggest that computer electromagnetic radiation may increase ROS level in semen and impair sperm morphology and fertilization capacity in male adult.