We determined the prevalence of anorexia nervosa and bulimia in a large sample of students attending a secondary school on the island of São Miguel (Azores) using the Diagnostic Interview for Children and Adolescents, which enabled us to collect the information necessary to make DSM-III diagnoses. Although the prevalence of anorectic and bulimic behaviour was rather high, the partial syndrome of anorexia nervosa was found in only 0.48% of the students (0.76% for girls and 0.17% for boys) and the syndrome of bulimia in only 0.16% (0.30% of the girls; there were no boys with bulimia). The overall prevalence of eating disorders, including partial syndromes, was rather low (0.64%). These results stand in sharp contrast to reports that eating disorders are common and probably getting more common. The low prevalence found in the present survey is probably due to the absence of sociocultural pressures to control eating and weight.