Objective: To improve estimates of vitamin A deficiency in children of pre-school age in the 2006 Uganda Demographic and Health Survey (UDHS 2006). Design: A cross-sectional study in which dried blood spot samples were analysed for C-reactive protein (CRP). Retinol-binding protein (RBP) had previously been analysed using a commercial enzyme immunoassay. Setting: A population-based study in Uganda. Subjects: A systematically selected subset of the dried blood spot samples collected from children aged 6-59 months for UDHS 2006. Children were categorized into 'normal CRP' (Group A) and 'raised CRP' (Group B) using a CRP cut-off of 5 mg/l. A correction factor was calculated to adjust the Group B RBP values for the influence of the acute-phase response. Results: Geometric mean CRP was 6?2 (95 % CI 5?5, 7?0) mg/l, 1?6 (95 % CI 1?5, 1?8) mg/l and 17?9 (95 % CI 16?4, 19?6) mg/l in all children, in Group A and in Group B, respectively. Geometric mean RBP in all children, in Group A and in Group B was 1?18 (95 % CI 1?14, 1?22) mmol/l, 1?26 (95 % CI 1?20, 1?33) mmol/l and 1?12 (95 % CI 1?07, 1?17) mmol/l, respectively, before correction. Correction increased mean RBP in Group B to 1?26 (95 % CI 1?21, 1?31) mmol/l. The prevalence of vitamin A deficiency (RBP , 0?825 mmol/l) reduced from 18?4 % (95 % CI 17?2, 23?0 %) to 13?9 % (95 % CI 11?3, 16?5 %). Conclusions: Correcting for the acute-phase response significantly reduced the prevalence of vitamin A deficiency; thus, the acute-phase response should be considered when vitamin A status is assessed using RBP in order to improve population-level estimates of vitamin A deficiency. (3) . The VAD prevalence estimate in children was 20?4 % (4) . Circulating concentrations of serum retinol (5)(6)(7) and RBP (8) decline in response to the acute-phase response and may not adequately reflect vitamin A status. These changes, which are an integral part of the acute-phase response, reflect decreased synthesis of RBP and increased excretion of retinol in urine (9,10) . Because levels of circulating acute-phase proteins (APP) can aid in the interpretation of low serum retinol levels, the simultaneous measurement of retinol and one or more APP is recommended (5)(6)(7)(11)(12)(13) . There is currently no consensus on how to correct retinol concentrations for the influence of the acute-phase response. Paracha et al. (11) proposed the application of new cut-offs for low and deficient retinol concentrations for children in whom a 1 -antichymotrypsin and a 1 -acid glycoprotein concentrations were elevated. In the approach proposed by Thurnham et al., individuals with normal APP levels provide the reference group for whom it is assumed that diet is the main factor responsible for the concentration of retinol. The median retinol value for the reference group is divided by the respective median values for groups at different stages of the acutephase response. Correction factors thus obtained were applied to apparently healthy HIV-1-positive adults with raised APP; the proportion with low...