The shape, diameter and length of normal internal auditory canal(IAC) are important for the evaluation of pathology including acoustic neuroma, but, up to now, there are no reports about the shape, diameter, and length of the IAC of the normal Korean through the plain X-ray. Here, we report the results of the radiological masurement of the IAC with the transorbital and the Stenver's projection. The results were as follows ; 1) The incidence of a variation in the shape was 59% of the cylinder, 29% of the funnel, and 12% of the bud shape in the transorbital view and was 69%, 2% and 29% in the Stenver's view. The same shape in both sides was 59% in the transorbital view and 73% in the Stenver's view. Coincidence of the same shape was 52% in both views. 2) The average largest diameter was 6.43±0.79mm in the transorbital view and 6.19±1.04mm in the Stenver's view. The difference of diameter in both views was 0.24mm, but it was not significant statistically(p>0.05). 3) Bilateral difference in the largest diameter was less than 1.0mm in 74%, 1~2mm in 22%, and larger than 2mm in 4% in the transorbital view and was 81%, 16% and 3% in the Stenver's view. 4) The average length was 10.10±1.88mm in the transorbital view and 10.17±1.30mm in the Stenver's view. The difference of length in the both views was 0.07mm, but it was not significant statistically(p>0.05). 5) Bilateral difference in the length was less than 2mm in 78%, 2~3mm in 18% and longer than 3mm in 4% in the transorbital view and was 61%, 9% and 30% in the Stenver's view.