The long term consequences of untreated of residual or recurrent lesions pose unique challenges in the growing population of adults with congenitally malformed hearts. In our unit, 335 patients aged from 18 to 72 years, with a mean age of 35 plus or minus14 years, presented for correction of congenital cardiac disease from September, 1997, through December, 2006. Of the group, 42 (12.5%) had undergone one or more prior surgical procedures, 3 were admitted as emergencies, and a further 10 (3%) had suffered prior cardiac related complications. Symptoms had been noted by 181 patients (54%), and 42 (12.5%) had an established arrhythmia. Chromosomal anomalies were identified in 13 (3.8%), and diagnostic catheterisation was required in 201 (60%) patients. Of the overall group, 2 patients died early (0.6%). Complications occurred in 61 patients (18%), including atrial fibrillation, pneumothorax, postoperative haemorrhage, pericardial or pleural effusions requiring drainage, stroke, complete heart block, endocarditis, wound dehiscence, and peripheral neuropathy. The median length of stay in the intensive care unit and hospital were 2 and 7 days, respectively. Death occurred later in 2 further patients (0.6%), due to atrial fibrillation and pulmonary hypertension. At mean follow-up of 63 plus or minus 30 months, the majority of the remaining patients are well with resolution or significant improvement in their symptoms. Despite the long term deleterious effects of untreated, residual or recurrent congenital cardiac lesions in adults, therefore, we conclude that surgical correction can be achieved with low mortality and acceptable morbidity. Most significant complications are related to arrhythmias.