The authors carried out a macroscopic study of the oculomotor nerve based on the dissection of 60 hemifaces with special emphasis on the numerous variations of the course of the nerve from its apparent origin to its termination in the orbital cavity. Histological study of serial sections of the nerve showed that a true fascicular structure exists only distal to the point where it pierces the dura mater. The number of histologically identifiable fasciculi was found to be highly variable from one subject to another and, in a given individual, from one side to the other.