The author studied the magnification ratio of teeth length in orthopantomogram through intraoral film taken by standardized paral1eing technique. In this study, intraoral radiograph and orthopantomogram were taken in 2 cases of dry skull and 36 adults (504 teeth). 1. The obtained results were as follows: In case of dry skull, the magnification ratio of standard films was 4.6% to 5.9% and that of Orthopantomograph 5 was 15.1% to 33.1%. The magnification ratio of to the standard film was 9.2% to 26.5% 2. In case of adults, the magnification ratio of Orthopantomograph 5 to the standard films was 9.5% to 24.6%. 3. There were no significant difference in magnification between left and right. 4. Anterior teeth had lesser magnification than posterior teeth. 5. It was considered that teeth length showed in Orthopontomograph 5 was magnified 15.4% to 31.3% than actual teeth length.