We examined the effect of strenuous exercise on blood constituent. Studies were made on healthy 13 members (19 ~ 27 years) of the canoe club of Kansai Medical University who participated in summer training camp for 15 days. Blood samples were drawn from an antecubital vein before and after training camp. After training camp, total protein, albumin and total cholesterol were significantly decreased, and total electrolyte (Na + K + Ca)were not affected. Serum GOT and GPT activities were not change but LDH and CPK activities were significantly increased. Hb and Ht values were significantly decreased and serum Fe level showed a tendency to decreased. Serum Zn level were significantly decreased but Se and Cu level were not changed. Serum antioxidative substance (ascorbic acid and α-tocopherol) levels were significantly decreased, while lipid peroxide level (malondialdehyde) was significantly increased. These data suggest that strenuous exercise can result in a reduction of nutritional status and an induction of oxidative damage.