Vitamin B1, B2, B6, C, A, and E status was assessed by combining determination of dietary intake with biochemical indices in 55 young male athletes. When compared with 20 matched sedentary controls, a similar number of individuals with biochemical deficiency was found in both groups for vitamins B1, B6, and E despite a higher mean dietary intake of these three vitamins in young athletes. Markedly reduced levels of pyridoxal 5'-phosphate, the biologically active form of the vitamin B6compounds, were found in both populations. Supplementation administered for one month improved the vitamin status of the control subjects but not entirely those of the young athletes.