['To study the relationship between polyunsaturated fatty acids (PUFA) status and depression in adolescents with eating disorders (ED) and weight loss.', 'Erythrocyte membranes from 217 adolescents (209 girls, eight boys) with ED were analysed for fatty acids (FA). ED and depression were diagnosed by clinical interviews and supported by self-report instruments.', 'Adolescents with ED and depression did not differ from those with ED only in terms of age, BMI, weight loss and duration of disease. In their FA profile, depressed adolescents had lower proportions of eicosapentanoic acid (EPA) and docosahexanoic acid (DHA), the end products of the ω3 PUFA series. The ratio of long-chain (>18 carbons) ω6/ω3 PUFA was therefore higher in depressed adolescents. Indices of desaturase activities did not differ between depressed and not depressed adolescents.'] Are omega-3 polyunsaturated essential fatty acids associated with depression in adolescents with eating disorders and weight loss?