This study was conducted to assess effects of aluminum (Al) exposure on allergic responsive reactions and humoral immune function in rats. Forty male Wistar rats (5 weeks old) weighed 110-120 g were randomly allocated into four groups 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. The levels of immunoglobulin (Ig) G, IgA, IgM, IgE, Complement factor (C)3, and C4 in serum were determined by ELISA and nephelometric assays at the end of experiment. The results showed that the levels of IgM, C3, and C4 were lowered, and the levels of IgG, IgA, and IgE were increased in an Al-dose dependent manner. The increased in IgE level and the decreased in C3 and C4 levels indicate that Al induces allergic responses in rats; while the increased levels in IgG and IgA and the decreased level in IgM suggest that Al disorders the humoral immune function in rats.