Aim: To determine the combined mesio-distal width of the permanent mandibular incisors and that of the maxillary and mandibular canine and premolars in the permanent dentition stage among a sample of the Egyptian population in El Menia governorate, and to find the correlation between them, as well as to develop new regression equations.Materials and methods: A total of 200 children (100 boys/ 100 girls) were selected from preparatory schools from El Menia governorate. Their age ranged between 12-15 years old. After data collection, results of our sample were compared to those of Tanaka and Johnston’s equation, to check its accuracy and applicability on a sample from the Egyptian population, and new regression equations were derived based on the collected data.Results: Results of this study showed that there was a positive correlation between the mesio-distal widths of all teeth in male and female subjects.Conclusion: This study concluded that there is positive correlation between the mesio-distal widths of the teeth under study, also Tanaka and Johnston’s prediction method was not accurate when applied to a sample from the Egyptian population, and new regression equations were derived to estimate the mesio-distal width of unerupted permanent canine and premolars in Egyptian children.