OBJECTIVES There is little information in the literature on the long-term outcome of young patients undergoing coronary bypass grafting surgery. The aim of this study is to analyze the long-term clinical outcome of this technique when performed in young adults. METHODS We included in this retrospective study all patients aged 40 years or younger undergoing coronary bypass surgery in our unit between January, 1989 and December, 2006. Relevant clinical data were retrieved from the patients' clinical records. Follow-up data were obtained by means of personal or telephone interviews with the patients themselves or with their relatives. RESULTS There were 42 patients (3 females, 39 males), mean age 36.9 years (range 29-40 years). Nineteen of them suffered a previous myocardial infarction. Left ventricular function was impaired (ejection fraction lower than 50%) in six instances. Twenty-two patients underwent surgery in a state of unstable angina. The indication for surgery was 3-vessel disease in 17 patients, 2-vessel disease in 17 patients and single-vessel disease in seven instances, and in six cases the main steam of the left coronary artery was affected. A total of 102 grafts were constructed (mean 2.4 grafts per patient), 56 (54.9%) of them being arterial. There were no hospital deaths. Mean hospital stay was of 8.1 days. Four patients suffered relevant perioperative complications. One patient (2.3%) was lost for follow-up. Cumulative follow-up was 389.1 years, with a mean of 9.5 years per patient. There were five late deaths, all of them of cardiac origin, with an estimated actuarial probability of survival of 81.4%. Thirteen patients suffered 17 major cardiac non-lethal complications, with an estimated actuarial freedom from cardiac morbidity of 43.9%. Major peripheral vascular morbid events occurred in nine patients, the estimated actuarial probability of freedom from peripheral vascular complications being of 62.1%. Overall actuarial freedom from any cardiovascular lethal or morbid event was estimated at 27.7%. CONCLUSIONS Peri-operative mortality and morbidity is low in young patients undergoing coronary bypass surgery. However, these patients present a high risk of suffering major adverse events of cardiovascular origin in the long-term.