Eighteen of 22 patients with stenotic gastrojejunostomies following gastric bypass surgery were successfully corrected by endoscopically placing a guidewire through the narrowed outlet and then passing a dilating balloon catheter over the wire. No complications occurred. All procedures were done without general anesthesia, and 64 per cent were done without hospitalization. This procedure can spare patients prolonged hospitalization for nasogastric decompression or reoperation, the two standard approaches to this problem. Successful use of this technique to dilate obstructed gastric partitions and distal esophageal strictures suggests that it may be considered for any gastrointestinal stenosis within reach of the endoscope.