Objective: To determine provisional estimates of the extent of vitamin A (VA) deficiency and xerophthalmia among school-aged children. Design: Literature search of published, unpublished and website-based population survey and study reports, with country-specific imputation of prevalence rates and numbers of children affected by: ( 1) VA deficiency based on measured or imputed distributions of serum retinol concentration <0.70 mu mol/l ( equivalent to <20 mug/dl) and ( 2) xerophthalmia, by country. Setting: Countries within the WHO South-East Asian Region. Subjects: The target group for estimation was children 5 - 15 y of age. Interventions: None. Results: The estimated prevalence of VA deficiency is 23.4%, suggesting that there are similar to83 million VA-deficient school-aged children in the region, of whom 10.9% ( 9 million, at an overall prevalence of 2.6%) have mild xerophthalmia ( night blindness or Bitot's spot). Potentially blinding corneal xerophthalmia appears to be negligible at this age. Conclusions: VA deficiency, including mild xerophthalmia, appears to affect large numbers of school-aged children in South-East Asia. However, nationally representative data on the prevalence, risk factors and health consequences of VA deficiency among school-aged children are lacking within the region and globally, representing a future public health research priority.