OBJECTIVE To study the prevalence of eating disorders among adolescent in a health area. Design. Cross-sectional descriptive study.Setting. The primary care centres of secondary education. METHODS Students with age between 13-16 years. METHODS The validation of the Spanish translation of the Eating Attitudes Test-40 was administered to students, previous authorization of their parents. In the positive cases, we reported with a letter to their parents. The date were incorporate to a data base and in order to their treatment tools of analytic and descriptive statistic they were used. RESULTS There were 503 valid questionnaires (95% students of the health area). The absolute mean score was 13.42 points (CI, 12.57-14.28), in women 14.71 points and in man 11.82 points. According to age groups, the mean score for 13, 14.15 and 16 years was 14.05, 13.85, 13.08 and 12.60 points respectively. 16.97% presented >= 20 points (sensitivity, 91%; specificity, 69.2%) and 16.97% of the sample >= 30 points (sensitivity, 67,9%; specificity, 85.9%). There were more positive cases in women than men (2 = 22.4; p < 0.001). The age variable did not show statistically significant differences (2 = 3.379; p > 0.05). CONCLUSIONS There is a high prevalence of eating disorders among secondary students, being more frequently among women. We think it is necessary to make preventive services task in these problems and seek positive cases.