A case of occult bleeding of the upper intestinal tract in a patient with secondary polycythaemia and aortic valve stenosis is described. Routine tests failed to disclose the origin of the bleeding and the patient's condition continued to deteriorate. On the 23rd day after admission, laparotomy was performed, and an ulcerated diverticulum diagnosed. Resection of the diverticulum was done immediately. The patient had an uneventful post-operative recovery and was dismissed from the hospital 15 days later. Our experience underscores the necessity for early laparotomy in cases of gastrointestinal bleeding of obscure origin.