Left atrial isomerism includes a complex spectrum of cardiac and extracardiac anomalies. The records of all patients with left isomerism born during the period of 1973–2010 and treated at the Children’s Hospital, Helsinki were reviewed. The short- and long-term outcomes were studied. The review included 38 patients (50% females). The overall survival with left atrial isomerism was 63% during a median follow-up time of 16 years (range, 4–30 years). Extracardiac anomalies were noted in 14 (37%) of 38 cases. Cardiac defects included dextrocardia in 26%, partially or totally anomalous pulmonary venous return in 29%, common atrium in 50%, atrioventriculoseptal defect in 73%, single ventricle in 40%, ventriculoseptal defect without atrioventricular defect in 11%, transposition in 21%, double outlet of the right ventricle in 26%, pulmonary stenosis or atresia in 61%, and left ventricular outflow obstruction in 24% of the cases. Cardiac arrhythmias were presented in 71% and pacemaker treatment in 29% of the cases. Of the 38 patients, 33 had cardiac surgery. Simple palliative methods were used in 11 cases, single-ventricle palliation in 12 cases, and operation with a biventricular track in 10 cases. In the groups that had surgery, 3 of 11 patients, 3 of 12 patients, and 3 of 10 patients died, respectively. In this review, 14 deaths occurred, associated with extracardiac anomalies in five cases and with cardiac arrhythmia in four cases. Five postoperative deaths occurred. At this writing, all three patients who had heart transplantation are alive. Complicated heart defects associated with severe arrhythmias and extracardiac anomalies contribute to a high mortality rate with left isomerism. Cardiac transplantation was considered a good option for selected patients.