The vascularity of the facial canal in the rat was studied with the microcorrosive technique and scanning electron microscopy. The vascular casts thus created demonstrated the larger feeding vessels and the extrinsic vascular supply, but gave above all a good three-dimensional comprehension of the fine blood vessels within the nerve proper, the intrinsic vascular supply. The facial nerve is supplied by a rich anastomosing network of these fine blood vessels. Vascular loops and arteriovenous anastomoses are common, thus avoiding the creation of end-arterial systems. The blood vessels of the facial nerve also communicate widely with the rest of the temporal bone through small bony canals present in the lining of the facial canal. The architecture and distribution of the fine blood vessels are of great clinical interest, especially with regard to the etiology of idiopathic peripheral facial palsy, since it is at this level that the exchange of fluids, elecrolytes, and metabolites takes place.