Twenty-five teenagers, 13 males and 12 females, some obese and others overweight, aged between 12 and 18 years, were studied over 8 months, under the supervision of a multidisciplinary team. Effects of re-education in eating habits and physical activity on the lipid profile were evaluated. Dyslipidaemia characterised by increased levels of total cholesterol, low-density lipoprotein cholesterol and triglycerides was obeserved in 64%, 12% and 44% of the teenagers, respectively. Whereas decreased levels of high-density lipoprotein cholesterol were observed in 28%, tendency to hypertension has been observed in 36% of the teenagers. After 8 months, the number of teenagers with total hypercholesterolaemia and hypertriglyceridaemia decreased to 32% and 24%, respectively. Low-density lipoprotein cholesterol levels did not vary significantly. High-density lipoprotein-cholesterol levels increased in 17% of participants. Reduction of blood pressure occurred in most teenagers. These data suggest that re-education programmes in eating habits associated with changes in behaviour and physical activity can benefit obese teenagers and prevent various diseases.