Introduction: Overweight and obesity are major risk factors for a number of chronic diseases, including diabetes, cardiovascular diseases and cancer. Objective: to determine the prevalence and association factor of obesity/overweight in Arada sub city privet high school in Addis Ababa Ethiopia. Methodology: The present study was Institution based cross sectional study it was conducted among private school student and data was collected from 448 children. A structured pre-tested questionnaire was used for data collection. The data was entered and analyzed using SPSS version 20. Result a total of 448 students was participated in the study with a response rate of 100%. The overall prevalence of overweight and/or obesity was found to be 59(13.18%) The overweight prevalence was higher among girls (8.93%) than boys (0.89%); while 0.89% girls and none of the boys were obese. CONCLUSIONThere was a strong association of this prevalence with Family size, Educational status of the parents, walking for 30min, physical activity level and sex of the house hold RECOMMENDATION Integration of nutritional education in every curriculum of the school and Periodic screening for overweight and obesity.