Abstract: In order to study the noxious effects of profenofos on human erythrocyte membrane,the activity of erythrocyte membrane complement receptor type 1(Em-CR1)and erythrocyte superoxide dismutase(E-SOD),the level of erythrocyte membrane sailic acid(Em-SA) and erythrocyte membrane lipid fluidity were determined.The results showed that certain concentration of profenofos may obviously decrease above-mentioned indices and appear the relationship of dose-effect.It prompted that Profenofos has a obvious toxicity on human erythrocyte membrane.