Objective: This study was conducted to compare vertical and horizontal periodontal measurements of posterior teeth on standardized panoramic and intraoral radiographs. Methods and materials: Standardized panoramic and periapical radiographs were made of 16 human skulls using ball bearings placed on the maxillary first molars to allow adjustment for horizontal and vertical magnification. Results: At 14 of 19 measurement sites there was no significant difference between measurements on the 2 radiographic film types. At 4 sites vertical measurements on panoramic radiographs were significantly larger than on periapical radiographs (0.80 to 1.37 mm). At one site horizontal measurements were significantly greater on periapical radiographs (0.88 mm). Conclusions: If there is adjustment of the raw data for magnification as suggested in this study, panoramic radiographs may be used for measurement studies in the posterior region once the patients are positioned appropriately within the focal trough of the machines and the magnification range for the posterior focal trough is used for adjustment of data. Keywords: panoramic radiograph, periapical radiograph, posterior teeth