Gastrointestinal mechanical activity was studied in 13 patients after different surgical procedures in a fasted and fed state and after pharmacological stimulation. Mechanical activity was recorded by means of a multi-pressure sensor probe placed intraoperatively into the jejunum. Abdominal surgery abolished normal motility only for a short period of time. The time for the reappearance of regular recurring activity fronts varied with the type of the surgical procedure from 3 hr after cholecystectomy to the sixth postoperative day after colon resection. The fed pattern occurred after the first postoperative interdigestive motor complex in all experiments. Stimulation was observed with ceruletide, which induced contractile activity in the small intestine during postoperative ileus. No coordinated caudad propagating activity was observed. The postoperative interdigestive motor complex did not correlate in time with the first passage of flatus and stool in our patients. Thus, the restoration of motility in the small intestine did not coincide with the clinical relief from the so-called "physiological" postoperative ileus.