Expanded polytetrafluoroethylene (PTFE) (Gore-Tex) grafts were used in 16 patients with ischemic heart disease undergoing aorta-coronary bypass graft operations. PTFE was used only when insufficient suitable vein was available. A total of 27 grafts were inserted in 16 patients. Eighteen grafts (in 11 patients) were studied in the early (3 months) postoperative period. Eleven were patent. Nine expanded PTFE grafts in six patients were restudied between 12 and 29 months after insertion. Six were patent. Factors affecting graft patency were similar to those governing patency of vein grafts. There was a high incidence of complications, but the patients constituted a poor-risk group. It is reasonable to use expanded PTFE grafts when insufficient vein is available. Such grafts can remain patent and functional for at least 2 years.