Clinical features and natural history were analyzed in 30 patients with Ebstein's anomaly (mean age 26 years, range 1.5-58 years, 53% females). The main presenting symptoms were dyspnea and fatigue (83%). At presentation, there were six patients (20%) in New York Heart Association Functional Class (NYHAFC) I, nine (30%) in NYHA-FC II, and 15 (50%) in NYHA-FC III or IV; 12 patients (40%) were cyanotic. Common auscultatory findings were widely split second heart sound in 21 (70%), third heart sound in 14 (47%), fourth heart sound in 16 (53%), and a systolic murmur in 22 (73%). Right bundle branch block was present in 21 (70%), documented supraventricular tachycardia in seven (23%), and Wolff-Parkinson-White syndrome in three (10%). Catheterization was performed in 93% without complications. Fourteen patients were treated surgically (12 [86%] in NYHA-FC III or IV, 10 [71%] with associated anomalies); tricuspid valve replacement was performed in eight, atrial septal defect repair in two, accessory pathway ablation in two, right atrial plication in one, and automatic cardioverter defibrillator implantation in one. Surgical treatment improved 10 patients from NYHA-FC III or IV to NYHA-FC I or II. Death occurred in nine patients (five treated surgically and four medically); four of these deaths were sudden. In the eight patients who had tricuspid valve replacement, there were one operative and two late deaths. The authors conclude that surgical therapy with tricuspid valve replacement improves the clinical status of patients who are severely ill. Risk of sudden death remains an important problem in patients with Ebstein's anomaly regardless of severity of the disease and mode of treatment.