Micronutrients (zinc, vitamins A and E) and related proteins (retinol binding protein (RBP), prealbumin, albumin) were measured in the serum of African children with measles, and the changes induced in these by vitamin A supplementation (offered in a randomised, double blind, placebo controlled trial) were studied. All these substances were significantly reduced early in the exanthem in measles patients as compared to controls; they attained control values by day 8 after the rash, except for serum albumin which became normal by day 42. Vitamin A and prealbumin levels on day 8 were significantly increased in the supplemented over the placebo group. Vitamin A levels in serum correlated with those of RBP, prealbumin and zinc. These findings strengthen the hypothesis that hyporetinemia during measles is the consequence of impaired mobilisation. Our results indicate that our patients did not have pre-existing low liver stores. Accordingly, the results obtained here provide rational support for the recommendation that vitamin A should be given to all children with severe measles, even in communities where vitamin A deficiency is not a recognised public health problem.