Background: Assessment of dental developmental stage is more valuable than tooth eruption because the duration of tooth eruption is short and is determined by the appearance of tooth in the oral cavity. Among the different methods that could be used to determine the developmental stage of teeth, the Demirjian’s method has been extensively applied. This study aimed to assess the developmental stage of homologous mandibular first and second molars in 5 to 12-year olds using the Demirjian’s method.Methods: This cross-sectional study was conducted on 300 panoramic radiographs of 5 to 12-year-old Iranians obtained from the Radiology Department of Hormozgan University of Medical Sciences from March 2019 to April 2020. The developmental stage of homologous mandibular first and second molars teeth were scored based on Demirjian’s stages. The observers were first calibrated for use of the Demirjian’s method and then the inter- and intra-examiner reliability and the respective kappa values were calculated after observing 300 panoramic radiographs. The radiographs were assessed twice with a one-month interval. The collected data was analysed using SPSS version 22 (SPSS Inc., Chicago, IL).Results: Significant difference was noted in the developmental stage of the first and second molars in the right and left side among the different age groups. According to the results, there was not a significant difference in the developmental stage of the first molars in right and left side between two genders while the difference in this regard between the mandibular right and left second molars between two genders was significant. Moreover, there was a significant difference in the development of the first and second molars in the right and left side between the four distributed age groups for each gender.Conclusion: According to the findings of this study, evolution of mandibular first and second molar is not an appropriate indicator for gender segregation in children under 12 years old, but it can be used in ages estimation. Therefore, it can be concluded that gender is an impactful factor on the growth process of the second molar on the left and right in this age group.