Preschool children (aged 3-6 y) who were living in an informal settlement within metropolitan Durban, South Africa, were assessed for vitamin A status. The serum retinol concentration of 169 children tested was 0.73 +/- 0.26 mumol/L (mean +/- SD). Nine children (5%) had vitamin A deficiency (< 0.35 mumol/L) and 75 children (44%) had low vitamin A concentrations (< 0.70 mumol/L). Conjunctival impression cytology (CIC) in 185 children revealed that 18% had poor vitamin A status as defined by two abnormal conjunctival specimens. The CIC test was a feasible and reproducible method; however, it correlated poorly with the traditionally accepted serum retinol threshold of deficiency in this population where overt vitamin A deficiency is not prevalent. This survey demonstrated that regardless of the measurement tool, there is a prevalence of subclinical vitamin A deficiency in this typical periurban informal settlement and accordingly we suggest that these children should be targeted for vitamin A-intervention strategies.