Background: Zinc deficiency, common in developing countries, is associated with decreased immunocompetence. Zinc supplementation benefits children with acute and persistent diarrhea and prevents pneumonia. Most deaths from vaccine-preventable diseases are from measles and whooping cough; pneumonia is the most common complication of measles and often the proximate cause of related deaths. Objective: We evaluated the effect of zinc supplementation on episodes of illness in children with measles accompanied by pneumonia. Design: In a double-blind, randomized controlled trial, children aged 9 mo-15 y who were admitted to the Infectious Diseases Hospital in Calcutta with clinically severe measles accompanied by pneumonia and who had been ill for ≤7 d were randomly assigned to receive zinc (20 mg, in elemental form as acetate, twice daily for 6 d) or a placebo. All patients received standard treatment with antibiotics and an initial 100 000-IU dose of vitamin A (as palmitate) by mouth. Results: Time-to-event analysis using the Cox proportional hazards model (42 in the zinc group and 43 in the placebo group) showed that the time needed for the resolution of fever and tachypnea, the return of appetite, and the achievement of a "much improved" or "cured" status was not different between the 2 groups. A high proportion of children had low serum retinol and zinc concentrations. Improvement in serum zinc and retinol concentrations after 6 d of treatment was not different between the 2 groups. Conclusion: Children with severe measles accompanied by pneumonia treated with antibiotics and vitamin A did not show any additional benefit from also receiving a zinc supplement.