This year marks the 75th anniversary of the discovery of vitamin A by E.V. McCollum. Interest over the past 40 years has focused almost exclusively on the ocular complications of deficiency. Recent data from Indonesia, India, Thailand, Tanzania, Guatemala and elsewhere are reorienting concerns. Observational studies indicate that vitamin A--deficient children grow poorly, are more anemic, have more infections and are more likely to die than their peers, and that the magnitude of many of these consequences is directly related to the severity of the deficiency, even after adjusting for other variables. The few supplementation trials completed to date support these conclusions. Even after excluding children with frank deficiency at baseline, vitamin A-supplemented children have grown faster, developed higher hemoglobin values, and died less frequently (by 30-60%) than their nonsupplemented peers. The great surprise is not the central role vitamin A plays in each of these areas (McCollum and others recognized this long ago), but that this single nutrient can so profoundly affect children who are subject to multiple adverse influences.