A questionnaire was developed to measure main areas of nutritional knowledge. Fifty‐six patients with DSM‐III diagnoses of anorexia nervosa, bulimia, or atypical eating disorders and 144 normal controls completed the questionnaire. Item analyses of a condensed form of the original instrument indicated satisfactory reliability of total scale and subscales. Patients with anorexia nervosa or bulimia had significantly higher mean scores for nutritional knowledge than controls on subscales “Macronutrients and Roughage” and “Calories” but did not differ from them on the subscale “Micronutrients and Vitamins.“ Patients with bulimia and patients with anorexia nervosa had equivalent scores. About 15% of anorectic or bulimic patients scored below the 25th percentile of normal controls. Implications for dietary management in eating disorders are discussed.