This study investigated the effects of vitamin C supplementation on immune status in smoking and nonsmoking male college students. Blood samples were obtained from 15 healthy smoking and from 15 healthy nonsmoking volunteers before and 4 weeks after vitamin C supplementation (1000mg/day). Daily nutrient intakes was also calculated. Plasma vitamin C, E, and A concentrations, white blood cells and subpopulations, lymphocytes and subpopulations, NK cell percentage,plasma immunoglobulin A, G, M and complement C3, plasma interleukin-2 , and prostagladin E2 were measured . Daily vitamin C consumption was lower in smokers than in nonsmokers. Vitamin C supplementation significantly increased plasma vitamin C in smokers, and increased NK cell percentage in smokers and nonsmokers. Plasma IL-2 concentrations were significantly increased by vitamin C supplementation in nonsmokers, and decreased helpe $r^pressor T cell ratio were decreased by vitamin C supplementatiion , but the differences were not significant. White blood cells and subpopulation percentage and plasma prostaglandin E2 concentration were not affected by smoking and vitamin C supplementation. These findings as nonsmokers.rs.