In the present studies, the acute toxic effects of 2-bromopropane (2-BP) and its analog, 1,2-dibromopropane (1,2-DBP), were investigated in female BALB/c mice. The mice were treated orally with either 2-BP at 2000 and 4000 mg/kg or 1,2-DBP at 300 and 600 mg/kg. Four days before necropsy, the mice were immunized intraperitoneally with sheep red blood cells (SRBCs). 1,2-DBP reduced the weights of the spleen and thymus weights and decreased the number of splenic cells. In addition, treatment with 1,2-DBP suppressed the antibody response to SRBCs. Meanwhile, only the antibody response was significantly suppressed by treatment with 2-BP. In the subsequent studies, the time course effects of 2-BP and 1 ,2-DBP on the hepatotoxic parameters were compared in female BALB/c mice. When mice were treated orally with either one of these chemicals for 6, 12, 24 and 48 h, the activities of serum alanine aminotransferase and aspartate aminotransferase elevated significantly only with 1,2-DBP 24 h after the treatment. The hepatic content of glutathione was reduced by 1,2-DBP. Meanwhile, these parameters were increased by 2-BP. The present results suggest that 1,2-DBP in the Solvent 5200 also contributes to the immnunotoxicity, although 2-BP is a major component.