Background The eruption pattern of temporary and permanent teeth are fairly constant with the growing age. So the age determination of an individual by examination of teeth is one of the accepted methods in legal system. A review of the literature shows there are differences in eruption pattern between different populations mainly due to variations in the constitutions and environment, so highlighting the importance of this study to the Nepalese population. Objective To assess the eruption age of temporary and permanent teeth in Nepalese population and compared the eruption age with other groups. Method This cross-sectional study, included 450 subjects, aged between six months to 25 years selected by simple random sampling method. The determinant variable such as age and number of teeth was recorded. Result Eruption of temporary and permanent teeth is slightly delayed in Nepalese population compared with others. First temporary tooth to erupt is lower central Incisor at around eight months and last to erupt is second molar at around 28 months. For permanent tooth, first molar erupts at around seven years and second molar erupts by 14 years. Eruption of third molar (wisdom tooth) varies from 18 to 25 years. Conclusion This study provides a model data on eruption age of teeth which is first study of its kind in Nepal. The findings of this study will help as a reference data for optimal use in clinical, academic and research activities especially in Nepalese population. Medico legally it helps in estimation of age along with other parameters.