In Bangladesh, high potency (200,000 IU) vitamin A is routinely supplemented to under-five children every 6 months. There are at least three large studies that failed to observe any effect of mega dose of vitamin A on the incidences and duration of diarrhoea and respiratory tract infections. In recent studies it has been shown that daily low-dose supplementation of vitamin A to malnourished under-five children produces similar or better effect, compared to high dose, during acute illness and also in preventing infectious diseases. Studies have observed higher mortality in high dose vitamin A supplemented group compared to the low dose group. However, they were done in smaller number of children [15, 44]. In serum, vitamin A remains saturated with RBP in a 1:1 ratio. Therefore, the amount of vitamin A in excess of this ratio, as would be expected in mega-dose supplementation of vitamin A to severely malnourished children with low serum RBP, would be non-functional at best, at least theoretically [19]. Two trials in Asia that used high dose vitamin A observed conflicting results. One study reported that, capsule distribution was not universal and probably vitamin A deficient children would be missed, and the response of the high dose was unlikely to be due to non-specific changes. In the other study, vitamin A supplementation alone failed to show any expected improvement of child survival in demographic data but they did not deny the importance of vitamin A supplementation in improving nutritional status [48, 49]. On the other hand, weekly supplement of 8,333 IU of vitamin A was reported to reduce mortality by 54% [50]. There thus is a need for a carefully designed study with adequate sample size to address the effect of low dose vitamin A on morbidity and mortality among severely malnourished children with diarrhoea and pneumonia- the basis of our proposed study. We hope that the results of this study will enable us to compare the cure rates of low-dose daily administration of vitamin A with that of the initial mega dose followed by daily low dose of vitamin A. Daily basal requirements (estimated amount which is needed to prevent signs of deficiency) for 0-1 and 2-6 years old children are 600 and 650 IU respectively, and the normal requirement (which is sufficient to maintain desirable levels of tissue store) for the same age group are 1200 and 1300 IU respectively [51]. It is estimated that malnourished children will lose 0.1µmol of retinol /day (97 IU) through urine during acute illness [24].