Vitamin A deficiency in children is associated with increased mortality and morbidity due to respiratory tract and diarrhoeal infections. Vitamin A supplementation has been shown in some studies to reduce morbidity due to respiratory diseases. However, other studies to reduce could not document such benefit from vitamin A supplementation. The role of vitamin A on immunity in humans is not yet clear due to inconclusive results. To evaluate immune changes and compare those with of a known immunopotent agent like zinc, a randomised double blind study will be carried out in 1-3 year aged children without acute illness and wt/age between 61% and 70% of NCHS standard. Baseline anthropometry and vitamin A status will be determined using MRDR test and immune status will be estimated. Each group consisting of 50 children will either receive vitamin A 200,000 IU over 7 days or 40 m elemental zinc daily for 7 days or both or placebo. After 8 weeks immunity test will be repeated. Immunity tests will include serum 1gA, 1gM, 1gG an lymphocyte simulation and 8 antigen multiple skin test. Undiminished children will be given measles vaccine and serum titre will be measured before and after supplementation. Vitamin A status will be estimated by MRDR test. Vitamin A2 will be given and 1ml blood sample will be collected after 5 hours to see the ratio of vitamin A1 and A2 (<0.06 as cut off) as the modified relative dose response (MRDR test). Doses of vitamin A or zinc will be repeated at the completion of 2 month. The results will be compared between groups and within groups at baseline and after 6 weeks. The study will generate information which will help to examine the immune response of vitamin A therapy in children as an underlying factor for reduction in mortality or morbidity. The study will be completed within a year.