We reported previously familial hypo-retinol-binding proteinemia in a child who developed keratomalacia during measles infection. In the present study, we characterized serum retinol-binding proteins (RBPs) in the affected family members and compared these RBPs with those in the unaffected family members. Immunoblotting following SDS-polyacrylamide gel electrophoresis and isoelectric focusing demonstrated no differences in molecular weight and isoelectric point between the RBPs from the affected and unaffected family members, as far as RBPs were detected by antibody against standard RBP. Gel filtration revealed that all the RBPs in the serum of the affected family members made a complex with prealbumin.