The present study was undertaken to assess the pubertal growth spurt in a group of Cairo school male adolescents, using the developmental stages of the middle phalanx of the middle finger (MP3) as a skeletal maturation index.This study was conducted as a part of research project between Ministry of Health and Faculty of Oral and Dental Medicine, Cairo University represented by Orthodontic Department. It included seven separate studies in different Egyptian governorates. This present study was conducted in Cairo governorate.A total sample of 1500 adolescent males was included in the research. Their circumpubertal ages were ranged from 11 to 16 years with mean age 13.6 years. Middle phalanx of the middle Finger (MP3) was digitally radiographed for each subject. Each film was interpreted to define its MP3 developmental stage and the data were collected and statistically analyzed.Based on the findings of this study, the following conclusions could be drawn :1. The mean skeletal maturity age (MP3-G stage) that represent the peak of height velocity(PHV)in Egyptian Cairo adolescent males was found to be 13.57 ± 0.95years which wasapproximately8,64 months after pre-peak stage . 2. The start of the pre-peak stage (MP3-FG) of pubertal growth was reached at 12.85 ±0.94 year. This means that the growth modulation treatment by functional orthodontic appliances should be done in male adolescent within range of 12.85y to 14.6y that represents the active period of pubertal growth between the pre-peak (MP3-FG) and the post-peak (MP3-H) stages respectively.