Objective To study the effects of cadmium on macrophage function. Methods Many indicators, such as phagocytic function, abilities to produce nitrous oxide and hydrogen peroxide, in mice were determined 14 days after they were administered continuously with 0.3, 0.6 and 1.2 mg/kg cadmiuCell count decreased in the mouse peritoneal lavage with the effects of cadmium chloride, with a significant difference, as compared with the control group. Phagocytic function of macrophage was inhibited significantly, with inhibition rates of 21.8%, 39.9% and 44.4%, respectively for various doses of cadmium, in a dose response pattern. The ability of microphage to produce nitrous oxide was significantly inhibited, also, with 61.90±27.83, 36.67±23.86, 46.60±13.33 μmol/L, respectively, as compared with 76.10±14.22 μmol/L in the control group. The ability of microphage to produce O - 2 was obviously inhibited by three different doses of cadmium, showing a dose response relationship ( r =0.979 0). The ability of microphage to produce hydrogen peroxide was inhibited only at a dose of 1.2 mg/kg of cadmium, with a significant difference as compared with the control group. There was a dose response relationship between cadmium and production of hydrogen peroxide, with a coefficient of regression (r) of -0.984 7. Conclusion Cadmium chloride, at the doses of 0.3, 0.6 and 1.2 mg/kg, could inhibit the phagocytic function of microphage, and the production of biological molecules, such as nitrous oxide, O - 2, and hydrogen peroxide. It indicated that cadmium chloride could directly affect the transmission of antigen and non specific defence function of macrophage.