The excision of parotid tumor under the preservation of facial nerve is difficult because of the pathohistological characteristics of the tumor and the anatomical structure of facial nerve. Recently, the incidence of facial paralysis has been reduced by refinements of technique including stimulation of facial nerve and the use of operating microscope. The easiest and safest way to identify the facial nerve is to look for its trunk at the level of emerging site from the stylomastoid foramen. But the study of anatomical correlation of the tympanomastoid fissure and the stylomastoid foramen was very rare. The authors studied anatomical correlation in the region of stylomastoid foramen and tympanomastoid fissure in 60 cases of temporal bone. The results were as follows ; 1) In 56.6% the bony ridge of the tympanomastoid fissure was flat form. 2) The stylomastoid foramen was located just below the tympanomastoid fissure in 71.7%, anterior in 21.7% and posterior in 6.6%. 3) The mean distance from the bony prominence of the tympanomastoid fissure to its terminal point was 6.8 mm and from this point to the stylomastoid foramen was 4.6 mm. 4) The mean anteroposterior diameter of the stylomastoid foramen was 3.3 mm and the transverse diameter was 2.6 mm.