A screening study was conducted to identify malnutrition in gastroenterology outpatients and to ascertain whether poor food intake is a contributing factor. A 48-hour recall method was used to collect dietary data from 154 patients (87 women and 67 men). Fourteen (16%) of the women and 8 (12%) of the men were classified as having protein-energy malnutrition (PEM) on the basis of abnormal anthropometric measurements or low serum albumin concentration. PEM was found in several diagnostic groups, but 9 of the 14 malnourished women had Crohn's disease. Protein undernutrition was more evident in women; calorie undernutrition was more evident in men. More women than men had low serum albumin levels. Low hemoglobin levels were particularly prevalent among patients with Crohn's disease. Many of the patients, especially women, had "inadequate" and "marginal" intakes of folate, vitamin A, thiamin, and calcium according to Nutrition Canada interpretive standards. The intake of iron was particularly poor among women: 59% of the intakes of female patients were classified as inadequate (less than 10 mg/day). Ten of the 14 female patients with PEM had inadequate iron intakes. Serum folates of less than 5 ng/ml were present in 72% of the women and 77% of the men. The data suggest that gastrointestinal outpatients are at high risk of malnutrition and that one of the factors contributing to the problem is inadequate food intake.