Coated pits (CP) and coated vesicles (CV) were investigated in the retinal pigment epithelium (RPE) of man and rabbit. In both species CP and CV show the typical coat of bristles radiating from their convex surface. CP originate only from invaginations of the basal and apical cell membrane. The bipolar distribution of CP is reflected in the distribution of CV which are most concentrated near the basal and apical cell boundaries. Neither fusion of CV with the cytoplasmic organelles nor the presence of receptosomes could be demonstrated. The distribution patterns of CP, CV, Golgi apparatus, and mitochondria are very similar in RPE of man and rabbit, as compared with other ocular tissues, CV found in RPE differ both in size and distribution from those found in the pigment epithelium of the pars plana ciliaris and in trabecular endothelial cells. This peculiarity might indicate that receptor-mediated endocytosis via CV plays a role in the transport across RPE of substances that are specific to this epithelium. Some analogies between the specificity of size and distribution of CV in RPE and the process of internalization and transport of retinol are suggested.