Swiss-Albino male rats were exposed to sulfur dioxide (SO2) (10 ppm) one hour daily for 60 days and the effect on the erythrocyte antioxidant enzyme activities was studied. Erythrocyte glucose-6-phosphate dehydrogenase (G-6-PD), superoxide dismutase (Cu,Zn-SOD), glutathione peroxidase (GSH-Px), catalase (CAT), glutathione-S-transferase (GST) activities and thiobarbituric acid reactive substances (TBARS) of 30 rats (14 controls and 16 sulfur dioxide groups) were measured. There were no significant differences in the catalase and G-6-PD activities of SO2 group as compared with controls. GSH-Px and GST activities in SO2 group were significantly higher than those in the control group. But, there was a significant decrease in the SOD activity. The rate of TBARS formation was enhanced significantly in erythrocytes of the SO2 group relative to the control group. These results reveal that SO2 inhalation enhanced lipid peroxidation in the erythrocyte and influence the antioxidant enzymes of erythrocyte.