This prospective study investigated the value of the hyperosmolar water-soluble contrast medium Urografin(®) in choosing which patients with small-intestine obstruction, caused by post-operative adhesions, to treat conservatively. Thirty-seven patients with adhesive intestinal obstruction received Urografin(®) via a nasogastric tube. Direct abdominal radiographs were taken after 2, 4 and 8 h. Twenty-four patients (64.9%) had Urografin(®) in the right colon within 8 h and were considered to have partial obstruction. These patients commenced oral feeding even though abdominal radiographs revealed gas-fluid levels. In the remaining 13 patients (35.1%), Urografin(®) was not observed in the right colon within 8 h: three of the 13 patients (23.1%) were successfully treated conservatively; 10 of the 13 patients (76.9%) developed toxic signs and underwent surgery, with obstruction resulting from adhesive bands being confirmed at operation. Conservative treatment can be recommended for patients in whom contrast medium is observed in the right colon within 8 h following administration, regardless of the presence of obstruction signs. Absence of contrast medium in the right colon within 8 h cannot, however, be considered an indication for surgery.