A morphometric studyon the trigeminal ganglion and the intracramial portion of the ophthalmic maxillary and mandibular nerves was bone in 50 Korean adult cadavers. The shape of the ganglion was classified into 7 types and semicircular shape was most cominn (54%) Mean width of the trigeminal root at porus trigeminus was 6.08mm The length of the trigeminal rot from porus was trigeminal ganglion was 8.28mm at ophthalmic portion 10.16mm at maxillary portion, and 8.90mm at mandibular portion. Maximum width of the ganglion was 15.48mm and the breadth of the ophthalmic and maxillary portion were 5.25mm and 5.26mm respectively, and that of the mandibulat portion(4.92mm) was narrower than the other portion. Inteacranial ophthalmic nerve was 4.30mm of width and 17.89mm of length Intracranial maxillary nervr was 5.41mm of width and 11.17mm of length, Intracranial manndibular nerve was 5.89mm of width and 5.43mm of length, and this nerve indlined average 39.7˚(range 14.56˚)from sagittal plane. It was observed infrequently that the cavernous sinus extended to the lateral border of the maxillary berve and the emissary sinus ran nuder the mandibular nerve.