The appearances of the colon on barium enema examinations in 7 patients with infectious colitis due to Salmonella and Shigella are described. The roentgenologic alterations of the upper gastrointestinal tract and small bowel were studied in 2 of the 7 patients. Diffuse involvement of the colon was seen in 2 patients and segmental disease with variable rectal and colonic involvement was present in the remaining 5. In general, the features were those of ulcerations, spasm and edema. The changes were found to be reversible in all patients who responded to therapy. These latter features of an acute colitis which may revert to normal should differentiate infectious colitis from both Crohn's colitis and ulcerative colitis.