The methods of retrograde fluorescent tracing and anterograde transport of the lectin Phaseolus vulgaris leucoagglutinin (PHA-L) were used to demonstrate the existence of projections from layers IV and VI of the entorhinal area to the hippocampal formation in the rat brain. These two layers of the medial and lateral entorhinal area innervate the molecular layer of Ammon's horn and the area dentata. In the area dentata the projection from layer IV follows that of the perforant path, while that from layer VI innervates the outer two-thirds of the molecular layer, the subgranular zone and the deep part of the hilus of the area dentata.