Impact of 6-monthly massive dosings of preschool-age children with oral vitamin A (VAC: 200,000 IU of oil soluble retinyl palmitate with 40 IU vitamin E) was evaluated in Bangladesh. In 100 sites, 11,889 households were visited and eyes of 22,335 children aged 3-71 mo were examined. About half the rural target population and less than 20% urban slum population were being reached. Risk of night blindness was halved for children reportedly given VAC, although 2.5% of the reportedly protected population were still night blind. There was no significant reduction in prevalence of Bitot's spot. Risk of corneal ulcers or keratomalacia (X3A/B) was 2.7 times higher in children not given VAC. Based on reported coverage, efficacy of protection against potentially blinding corneal lesions was 63%. For maximum impact on eye lesions, massive dosing with vitamin A at ideally less than 6-monthly intervals needs to be combined with other nutrition and health interventions.