Incidence, duration, and severity of diarrhea and respiratory symptoms were monitored weekly for 1 y in 15,419 children 6-60 mo of age in a randomized, placebo-controlled, masked clinical trial conducted in southern India. Half the children received weekly doses of 8.7 mumol (2500 microgram) vitamin A and 46 mumol (20 mg) vitamin E (treated) and the other half, 46 mumol vitamin E (control). Medical and ocular examinations and anthropometric measurements were obtained before and after 52 wk of intervention. Ocular examinations also were obtained after 26 wk. Supplements were delivered weekly from calibrated dispenser bottles by community health volunteers who also recorded each mother's recall of daily morbidity of her child during the previous week. Baseline characteristics of treated and control subjects were similar and documented a prevalence of 11% xerophthalmia and 72% undernutrition. Weekly treatment with the low-dose vitamin A supplement did not influence the incidence, severity, or duration of diarrhea or respiratory infections and did not influence linear or ponderal growth.