Overweight and obesity is an escalating health problem in both developed and developing countries. This descriptive cross-sectional study aimed to determine the prevalence of overweight and obesity among adolescents aged 13-16 years in Irbid governorate, Jordan, and to compare the prevalence by sex, residential area and socioeconomic status. In a cluster random sample of 1355 school students the prevalence of overweight and obesity (body mass index > or = 85th percentile) was 24.4% (15.7% overweight and 8.7% obese) and was significantly higher among female students, students who lived in urban areas and those with working parents. This high prevalence of overweight is a serious concern for public health in Jordan.