We examined whether angiotensin-converting enzyme (ACE) insertion (I)/deletion (D) polymorphism is associated with the development of myocardial infarction (MI) at < or = 35 years of age. The study sample consisted of 201 patients with premature MI and 140 age- and sex-matched healthy individuals. No difference was found in the distribution of ACE genotypes between the patients and controls. A higher prevalence of the DD genotype among hypertensives was found compared with the non-hypertensive patients (62.5% vs 35.6%, p = 0.01). ACE polymorphism is not associated with the development of premature MI and this might be due to the low prevalence of hypertension in young coronary patients.