Much has been learned during the past decade about the specific retinoid-binding proteins that exist in plasma and in the intracellular compartment in a number of tissues. Vitamin A is mobilized from liver stores and transported in plasma in the form of the lipid alcohol retinol, bound to a specific transport protein, retinol-binding protein (RBP). A great deal is now known about the chemical structure, metabolism, and biologic roles of RBP. A number of tissues of rats, humans, and other species contain soluble binding proteins with specificity for either retinol (cellular retinol-binding protein, CRBP) or retinoic acid (cellular retinoic acid-binding protein, CRABP). These intracellular proteins have been purified from several tissues and partly characterized. This paper provides a concise review of our current knowledge about the three retinoid-binding proteins, RBP, CRBP, and CRABP.