Positive radiologic findings were identified in the small and large bowels in three infants with various gastrointestinal manifestations of cow's milk protein/soy protein allergy, which was diagnosed on the basis of clinical features and histologic findings. Small bowel findings were thickened valvulae conniventes (plicae circulares), a ribbon-like ileum, and a thickened bowel wall. Narrowing, thumbprinting, and spasm were seen in the large bowel. These cases were seen at intervals far enough apart to exclude an endemic infection. The diagnosis of food protein allergy should be considered when diffuse small bowel disease or colitis is identified in an infant.