Cardiovascular risk factors were studied in a random sample from the urban and rural population of the Cap-Bon, including 692 men and women, aged 35-50 years. In this sample, including 56% urban dwellers, the mean total cholesterol was higher in urban areas (4.64 mmol/l) than in rural areas (4.16 mmol/l). In urban areas 10.2% of the subjects had values above 6.2 mmol/l compared with 6.6% in rural areas. Obesity was much more frequent among women (35.2% versus 26.3%) but less frequent among men (16.0% versus 5.4%) in urban and rural areas. Diabetes was found in 8.8% of men and 10.4% of women in urban areas, and only 0.8% and 3.9% in rural areas. Hypertension was found in 13.8% of women and 11.6% of men in urban areas, 13.3% and 4.0% in rural areas (13.3%). Cigarette smoking was found in 60.7% of men in urban areas and 75.8% in rural areas (p < 0.05).