We have reviewed 53 cases of allergic disorders of the gastrointestinal tract in children, including 15 with principal effects in the rectum (allergic proctitis) and 38 with dominant involvement of the upper and mid portions of the gut (allergic gastroenteritis). Most cases of allergic proctitis had their onset at less than 6 months of age, and all were under 2 years old when they presented with rectal bleeding alone or in combination with diarrhea. Rectal mucosal biopsy revealed in most cases a diffuse increase of eosinophils in the lamina propria together with a focal infiltration of the epithelium by eosinophils. Cases of allergic gastroenteritis affected all age groups and had a lower frequency of overt rectal bleeding. More common were other symptoms (vomiting, pain, and weight loss), an allergic history, anemia, blood eosinophilia, and increased serum IgE. Mucosal biopsy abnormalities were present in the gastric antrum in all cases sampled, the small intestine in 79%, the esophagus in 60%, and the gastric corpus in 52%. The lesions were usually diffuse and marked in the antrum and esophagus; in contrast, they tended to be focal and mild in the small intestine and gastric corpus. All cases of proctitis responded to a dietary change by cessation of symptoms without recurrences, whereas most of those with gastroenteritis had multiple relapses and required corticosteroid therapy.