This study assessed effects of aluminum (Al) exposure on the immune function of erythrocytes in rats. Forty male Wistar rats (5 weeks old) weighed 110–120 g were randomly allocated equally into four groups according to their weights and were orally exposed to 0, 64.18, 128.36, and 256.72 mg/kg body weight aluminum trichloride in drinking water for 120 days. Levels of erythrocytes C3b receptor rate (RBC-C3bRR), erythrocytes C3b immune complex rosette rate (RBC-ICR), erythrocytes rosette forming enhancing rate (ERER) and erythrocytes rosette forming inhibitory rate (ERIR) were determined by the end of experiment. The three Al-treated groups had lower values of RBC-C3bRR and ERER, and higher values of RBC-ICR and ERIR than those in control group. The levels of RBC-C3bRR and ERER decreased, while the levels of RBC-ICR and ERIR increased with the increases of Al content in drinking water. The results suggest that the immune function of erythrocytes in rats is suppressed by Al exposure.