OBJECTIVE--To study the immediate and long-term clinical success of percutaneous transluminal coronary angioplasty in patients aged 35 years or less. DESIGN--Patients undergoing percutaneous transluminal angioplasty were prospectively entered into a dedicated database. Clinical and angiographic data on all patients aged 35 years or less were reviewed. Follow up data were collected by interview during outpatient visits, by questionnaire, or from referring physicians. SETTING--A tertiary referral cardiac centre. PATIENTS--57 patients aged 35 years or less (median 33, range 22-35) underwent coronary angioplasty because of unstable angina (32 patients), stable angina (23 patients), acute myocardial infarction (1 patient), and documented ischaemia in a cardiac transplant patient. RESULTS--The primary clinical success rate (reduction in diameter stenosis to < 50% without in-hospital events) was 88%. A major procedure related complication occurred in 5 patients (9%): one patient died, two patients sustained an acute myocardial infarction, two patients underwent emergency bypass surgery, and in three patients repeat angioplasty was performed before hospital discharge. In 2 patients (4%) coronary angioplasty did not significantly reduce the diameter stenosis but there were no associated complications. A total of 60 lesions were attempted (balloon angioplasty in 57, directional atherectomy in 2). The initial angiographic success rate was 92%. The median (SD) follow up was 4.7 (3.0) years. During follow up 7 patients (12%) died, 10 sustained a myocardial infarction (18%), and 28 patients (49%) underwent repeat revascularisation (coronary artery bypass grafting in 7 (12%) and repeat angioplasty in 21 (37%)). The estimated 5 year survival and event-free survival (Kaplan-Meier method) was 87 (9)% and 50 (13)%, respectively. Multivariate logistic regression analysis showed that hypertension and the extent of vessel disease were the only independent predictive factors for event free survival. CONCLUSIONS--In young patients coronary angioplasty had a high immediate success rate but many needed repeat revascularisation procedures during the follow up period and survival was not improved. Coronary angioplasty in young patients should be regarded as a palliative procedure.