Statement of the Problem: Determining the crown-root ratio is crucial in many dental clinical decisions. There are no reliable data presented for Iranian population.Purpose: The aim of this study was to assess the root-crown ratio of permanent teeth with regards to the relationship of gender and jaw type using panoramic radiographs. The reliability of method was also assessed.Materials and Method: The crown and root lengths of teeth were measured by a digital caliper on panoramic radiographs of 185 individuals except for the third molars. A total of 1994 teeth was studied and 50.8% of the teeth belonged to males and 49.2% belonged to females. The modified Lind method was applied.Results: The highest mean root-crown ratios in both arches of both genders were obtained in the second premolars, followed by the first premolars and canines. In both genders, the lowest root-crown ratios were found in the maxillary central incisors. In male patients, the mean root-crown ratio was higher (p= 0.003) than that of females. Using Bland-Altman analysis, a non-significant difference of 0.006 (95% CI: -0.012-0.024) and 0.0002 (95% CI: -0.011-0.011) were found for intra-observer and inter-observer agreement, respectively.Conclusion: Assessment of the root-crown ratio in permanent dentition could be performed on panoramic radiographs with acceptable reproducibility in an Iranian Population. Considering observed differences, our findings suggest that for the accurate assessment, this ratio must be calculated for male and female patients and also for  the upper and lower jaws, separately.