We studied the factors related to delayed gastric emptying after operation for obstructing peptic ulcer disease. The records of 76 consecutive patients who underwent operation for obstructing peptic ulcer were examined retrospectively. Delayed gastric emptying (unable to tolerate solid food for at least 2 weeks after operation) occurred in 11 of 76 patients (14.5%). It was not related to the type of operation performed, including procedures that employed truncal vagotomy. It did not correlate with the preoperative severity of obstruction, duration of preoperative nasogastric decompression, or the nutritional status of the patient. Delayed emptying occurred in four of six patients (66.7%) with insulin-dependent diabetes mellitus but only 10 of 70 patients (14%) without insulin-dependent diabetes (p less than 0.001). It was seen in six of 16 patients (37.5%) receiving long-term cimetidine therapy (more than 3 months) but only five of 60 patients (8.3%) not receiving long-term cimetidine therapy (p less than 0.01). Patients receiving long-term cimetidine therapy had an average number of 2.3 prior hospitalizations for ulcer disease while those not receiving long-term cimetidine therapy had an average of 1.4 prior admissions (p less than 0.01). Thus we advise against the long-term use of cimetidine in chronic peptic ulcer disease complicated by obstruction. Patients with diabetes mellitus who require insulin appear to be at particular risk for delayed gastric emptying after operation for obstructing peptic ulcer.