We examined the effect of feeding a salmon-containing diet on the immune status of nine healthy men (age 30-65 years) who lived at the metabolic suite of the Western Human Nutrition Research Center for 100 days. During the first 20 days all nine subjects consumed a basal diet (BD). For the next 40 days, three subjects continued to consume BD, while the diet of remainder six subjects was modified to contain 500 g salmon every day. During the last 40 days, the diets of the two groups were crossed over. Feeding 500 g salmon daily for 40 days did not significantly suppress the blastogenesis of peripheral blood mononuclear cells cultured with phytohemagglutinin, Concanavalin A, protein A or pokeweed when compared to the corresponding pre-salmon diet values. It also did not significantly affect the delayed hypersensitivity skin response to seven recall antigens, serum concentrations of immunoglobulins G, M, and A, and complement fractions C3 and C4. Our results indicate that the short-term consumption of a high fish (salmon)-containing diet does not adversely affect the immune system, as has been reported with fish oil supplements.