Data are accumulating that support the hypothesis that inadequate zinc nutriture will result in an impairment of vitamin A utilization. Therefore, zinc and vitamin A status were assessed in 283 schoolchildren aged 7-13 y in Northeast Thailand. More than one-fourth had serum vitamin A concentrations less than 0.86 mumol/L , with a mean (+/- SD) concentration of 1.06 +/- 0.31 mumol/L compared with 1.26 +/- 0.02 mumol/L for US children of similar age. Seventy percent had low serum zinc concentrations, less than 10.7 mumol/L. Twenty-three percent of the children exhibited both low serum zinc and vitamin A concentrations. The mean concentration of retinol-binding protein (RBP) was lower for children in this study compared with healthy Thai children in Bangkok, 22.5 +/- 6.6 vs 25.3 +/- 6.0 mg/L, respectively. Serum zinc and RBP were significantly correlated (p less than 0.001) whereas vitamin A and zinc were not correlated. These data suggest that a high proportion of rural schoolchildren in Northeast Thailand are at risk of inadequate zinc and/or vitamin A nutriture.