Three women with idiopathic severe chronic constipation and inertia colica, who failed to respond to medical treatment, were extensively investigated for gut motor function, especially that of the colon. Twenty-four-hour manometric recordings disclosed that motility was severely reduced throughout the entire colon and response to eating was minimal. One of the patients also was tested for esophageal, gastric, and small bowel motor activity, which gave normal results. Edrophonium chloride stimulation (10 mg iv) provoked no increase in colonic contractile activity in any patient. On these grounds, the patients were submitted to surgical intervention (total colectomy with ileorectal anastomosis two, and left hemicolectomy the other) with fairly good results at follow-up. These results indicate the wisdom of carrying out extensive functional investigations in severely constipated patients before surgery is contemplated.