We studied the relation between angiotensin-converting enzyme insertion/deletion gene polymorphism and restenosis in Caucasian patients who underwent coronary angioplasty for management of unstable angina pectoris. Our results indicate that, in contrast to previous reports in Japanese patients, no association exists between angiotensin-converting enzyme gene polymorphism and the development of restenosis in Caucasian patients with acute coronary syndromes.)