AbstractPrealbumin is a so‐called rapid turnover protein which has a relatively short half‐life of two days. It has been shown to be a useful indicator of nutritional adequacy in premature babies. Retinol‐binding protein (RBP) and transferrin are two other rapid turnover proteins. The purpose of this study was to determine whether serum retinol‐binding protein and transferrin can be used for evaluating protein‐calorie adequacy in neonates, by correlating serial measurements of their concentrations with serum prealbumin concentrations. Prealbumin, transferrin and RBP concentrations were measured by a single radial immunodiffusion method. Our study showed that there is a significant difference in mean concentration of serum prealbumin between full‐term AFD (appro‐priate‐for‐dates) and SFD (small‐for‐dates) babies (p<0.05), but not in preterm babies. In normal birth‐weight infants, the concentration of RBP correlates positively with prealbumin (r=0.71), but this correlation was not observed in low birth‐weight infants (r = 0.58). We speculate that the concentration of RBP is an indicator of conditions other than protein nutrition. The serum concentration of transferrin does not correlate with prealbumin. Transferrin is a poor indicator of protein‐c