Knowledge of dental eruption pattern must be taken into consideration during occlusal development, malocclusion diagnosis and efficient treatment planning.Aim of the study: Determine the eruption dates and sequence of primary and permanent teeth and Correlate between chronological and developmental age of eruption of primary and permanent teeth in a group of children in Qalubia Governorate.Study Design: Cross sectional observational study.Subjects and Methods: The study sample consisted of 2212 healthy Egyptian children of both sexes, 1241 children were randomly selected from Qalubia governmental schools. And 971 children were randomly selected from children attending Maternal and child welfare centers. Children were selected according to certain criteria then examined and the status of the eruption of each primary & permanent tooth was recorded on a specially designed survey sheet.Statistical analysis: performed with IBM® SPSS® statistics version 20 for windows. Student's t-test was used for comparisons between mean ages of eruption in boys and girls. The significance level was set at P ≤0.05. One sample t-test was used to compare between mean ages of eruption of the study group and the standard values.Results: There was statistically significant difference in mean ages of eruption of primary and permanent teeth between boys and girls and between urban and rural areas. Sequence of eruption of primary teeth differed between boys and girls in urban areas and similar in rural areas. Sequence of eruption of permanent teeth differed between boys and girls in urban and rural areas.Conclusions: Chronological and developmental age were not usually coincident with each others. Degree of development of the areas may affect eruption dates as it was noticed in urban and rural areas.