In many of the urban centres of the developing countries, a change in lifestyle due to increased affluence has been observed. It has been shown that change in lifestyle is an important factor in the global epidemic of overweight and obesity. The aim of this study was to assess the influence of lifestyle and socioeconomic class on the prevalence of overweight and obesity amongst adolescents from rural and urban centres in Lagos, Nigeria. This is a cross-sectional prospective survey carried out on a sample of 1504 randomly selected adolescents, aged between 10 and 19 years, from six public secondary schools located in urban and rural areas of the Eti-Osa local government area of Lagos State, Nigeria. A self-designed completed questionnaire was used to determine the participants' socio-demographic characteristics. Anthropometric measurements were taken to calculate their body mass index (BMI). The overall prevalence rates of overweight and obesity in the urban and rural areas, respectively, were 3.7% and 0.4%, and 3.0% and 0.0%. Socioeconomic class did not significantly affect the BMI values. Overweight is an evolving problem, while obesity is seemingly not a problem yet in adolescent school-aged children in Lagos State, Nigeria.