The present study has been designed to investigate the timing of eruption of the first primary tooth in a group of Egyptian children, and to find the relation between the number of teeth erupted, age, sex, birth weight, somatic measures (body weight, height and Body Mass Index) and nutritional background of those children.Materials and Methods: The sample included (1173) Egyptian children aging from 6 to 18 months. This sample included (612) boys and (561) girls. The children were examined at the Internal medicine Clinics in Abu El Reesh Children’s Hospital, Faculty of Medicine, Cairo University. The mothers were interviewed using a standardized questionnaire specially designed for the purpose of the study. Information regarding birth weight and feeding pattern were obtained from the questionnaire. For each child the weight and height were measured to calculate the BMI.The results of the study showed that:1. The most influential factors affecting time and number of primary teeth eruption were birth weight, height, weight and feeding pattern.2. Infants with normal birth weights a significantly higher number of erupted teeth and earlier eruption times of the 1st primary tooth3. Breast fed infants showed a significantly higher number of erupted teeth and earlier eruption times of the 1st primary tooth