Background: Obesity is one of the most serious public health challenges of the 21st century and represents a serious health problem for low- and middle-income countries, particularly in urban settings. Its prevalence has increased at an alarming rate. Globally, more than 340 million children and adolescents aged 5–19 years are overweight or obese, and approximately two-third of them live in developing countries. Aim: The present study was implemented to assess the prevalence rates of overweight and obesity among adolescents in intermediate schools in Basrah, Iraq. Methods: A cross-sectional study was conducted during the second semester (between January 15 and May 30, 2013) among children attending public and private secondary schools in Basra city to determine the relationship between certain variables and the prevalence of overweight and obesity. Results: According to the study findings, the overall prevalence rates of overweight and obesity among adolescents aged 13–15 years in intermediate schools were 20.6% and 22.6%, respectively. Conclusions: A combination of decreased physical activity, sedentary behaviors (watching TV, playing video games, and using the internet), ingestion of unhealthy foods, and consumption of soft drinks may be responsible for the observed increased prevalence of overweight and obesity among adolescent students in Basra city.