Experiments were performed on mice to investigate the effect of Panax ginseng petroleum ether fraction on the immunotoxicity of lead acetate. Lead acetate was administered in the drinking water and ginseng p-ether fraction was injected intraperitoneally, Mice were sensitized and challenged with sheep red blood cell. Humoral immune responses were evaluated by antibody production and Arthus reaction. Pathotoxicological influences were measured by serum protein, alkaline phosphatase and total cholesterol. The weight of liver, spleen and thymus were measured. Lead acetate exposure significantly decreased hemagglutination titer, hemolysin titer, Arthus reaction, spleen and thymus weight. Ginseng p-ether fraction administration significantly restored or potentiated reduced humoral immune response, spleen and thymus weight. Reduced serum A/G ratio, total cholesterol and alkaline phosphatase activity were restored or increased by ginseng p-ether fraction administration.