Lipid peroxidation, antioxidant activities, and total fatty acids were investigated in the regenerating liver after partial hepatectomy in splenectomized male Wistar rats. The lipoperoxide levels were significantly lower in the splenectomized rats than in the non-splenectomized rats. The hepatic superoxide dismutase (SOD) activity was significantly higher in the splenectomized rats than in the controls, whereas the alpha-tocopherol content, and the activities of glutathione (GSH) peroxidase and catalase did not differ so widely between splenectomized and nonsplenectomized rats. In both groups, the fatty acid composition of the total lipids was not so different in the early stages of hepatic regeneration after partial hepatectomy, but it was noted that in the later stages of hepatic regeneration, polyunsaturated fatty acids tended to increase in the splenectomized rats. These results suggest that splenectomy attenuates lipid peroxidation, and tends to increase in polyunsaturated fatty acids in the remnant liver after partial hepatectomy, which may be attributable to high SOD activity, the maintenance of alpha-tocopherol, and the remaining activities of GSH peroxidase and catalase.