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 Design: Literature search of published, unpublished and website-based population survey and study reports, with countryspecific imputation of prevalence rates and numbers of children affected by: (1) VA deficiency based on measured or imputed distributions of serum retinol concentration o0.70 mmol/l (equivalent to o20 mg/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 B83 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 SouthEast 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.