1. A new protein which we call Interphotoreceptor Retinol-Binding Protein (IRBP) has been identified in the subretinal space. Significant light/dark differences in retinol binding to the 7S IRBP and to Cellular Retinol Binding Protein (CRBP) were observed in sub retinal compartments of the rabbit. 7S IRBP isolated from bovine retina has a molecular weight of approximately 243,000. SDS-polyacrylamide gel electrophoresis of this protein revealed a 146,000 MW and a 93,000 MW subunit. Retinol binding to 7S IRBP was first detected at the time of eye opening (13th postnatal day) in the C57 B1/6 mouse retina. 2. The IRBP could function as a vehicle for vitamin A transport between retina and pigment epithelium. A 14,800 MW unsaturated fatty acid binding protein was purified from developing chick neural retina.