It has been recently demonstrated that luteinizing hormone-releasing hormone (LHRH) can inhibit LHRH release by the hypothalamus, suggesting an ultrashort feedback of LHRH on LHRH neurons. In order to test this hypothesis, immunocytochemical localization of LHRH was conducted in the preoptic area of the rat brain. Contacts between endings and neuronal cell bodies staining for LHRH were observed. This direct interaction between LHRH neurons might be well the morphological basis for an autoregulation of the LHRH system in the rat brain.