To explore the relationships between obesity, socioeconomic status (SES), and physical activity (PA), we conducted a study with 341 subjects of a medium-size city of Benin and its semi-rural outskirts. PA was appraised with 24-hour recalls and SES, with a questionnaire. The overall prevalence of obesity (body mass index [BMI] = 30), abdominal obesity (waist circumference) and elevated percent of body fat (?) were 10.6%, 23.8% and 20.2%, respectively. However, 14.6% were underweight (BMI < 18.5). Overweight (BMI = 25) was significantly higher in urban than rural areas and in women than men. SES and PA were independently associated with obesity indicators, while urbanization variables were not.