The average concentration of retinol in the serum of 20 newborn Thai infants was 23.1 +/- 6.0 mug/100 ml, with a range of 14.3-36.6 mug/100 ml, about 60% that found in a group of healthy Thai women (39.8 mug/100 ml). Retinol containing components in pooled fetal serum and in adult serum were purified by chromatography first on DEAE cellulose and then twice on Sephadex G-100 columns. Over 90% of the retinol in fetal serum was associated with a complex between retinol binding protein and prealbumin. By several criteria fetal and adult retinol binding protein appear to be identical.