Reproduction and survival are influenced by parasites, and recently, the ability of the immune system to fight infection has been included in life history theory. A condition dependent immune response predicts tradeoffs within the immune system and condition dependent tradeoffs with other life history traits Female red jungle fowl (Gallus gallus) parasitized with an intestinal nematode (Ascaridia galli) had a higher concentration of eosinophils than controls, and parasitized and control females responded differently to rejections of phytohemagglutinin (PHA) PHA injections stimulated an increase in granulocytes in parasitized females relative to controls. Although parasitized females had greater circulating levels of the white blood cells that are involved in the cutaneous hypersensitivity response, control females exhibited greater swelling of the wing web six hours after injection. A. galli seemed to slow the cellular immune response to injections of PHA, suggesting a tradeoff within the cellular component of the immune system. Parasitized and control females differed in the relationship between immunoglobulin G (IgG) and the strength of the cutaneous hypersensitivity response. The decrease in cutaneous hypersensitivity with increasing IgG in parasitized vs control females suggests a condition dependent tradeoff between the cellular and humoral components of the immune system.