Smoking habits were studied in 1,274 healthy adolescents of both sexes, aged 10 to 18 years, of Fuenlabrada, Madrid. It was known by personal interview. 30% of the population were smokers. Smoking habits increased with age up to 18 years when 63% of males and 53% of females were smokers. Smoking prevalence was significantly higher among males than in females. Males and females smokers had significantly lower levels of C-HDL and higher levels of C-LDL/C-HDL ratio than non smokers. No differences were observed for anthropometric variables, body mass index, blood pressure, skin-fold thickness, total cholesterol, glucemia and uric acid. The implications of these findings are of concern in light of the apparently protective role of C-HDL in coronary heart disease. These findings provide valuable information to the promotion of antismoking campaigns in adolescent age.