Objective: To assess long term outcome of patients who underwent Mustard or Senning repair for transposition of the great arteries up to 30 years earlier. Design: Retrospective review of medical records. Setting: The six university hospitals in Belgium with paediatric cardiology departments. Patients: 339 patients were reviewed, of whom 124 underwent the Mustard procedure and 215 the Senning procedure. This represents almost the entire population of patients in Belgium with either simple or complex transposition. Main outcome measures: Mortality, morbidity, functional abilities, social integration. Results: Overall mortality was 24.2%. Early mortality (⩽ 30 days after surgery) accounted for 16.5%, late mortality for 7.7%. Actuarial survival of early survivors at 10, 20, and 30 years after surgery was 91.7%, 88.6%, and 79.3%, respectively. Patients in the Senning cohort had a slightly better survival rate than those in the Mustard cohort (NS). Baffle obstruction occurred more often after Mustard repair (15.3%) than after the Senning procedure (1.4%). Arrhythmia-free survival did not differ between the two cohorts, but was determined by the complexity of the transposition. Survivors of the Senning cohort had better functional status, and tended to engage in more sports activities. Conclusions: The long term outcome for patients surviving the Mustard or Senning operation was favourable in terms of late mortality, morbidity, functional, and social status. Overall mortality in the Senning cohort did not differ from the Mustard group, but Senning patients had better functional status, greater participation in sports activities, and fewer baffle related problems.