In patients with Ebstein's anomaly of the tricuspid valve, predictors of death and indications for surgery are poorly defined. We retrospectively reviewed 48 patients with Ebstein's anomaly, 17 (35%) of whom presented in the first week of life. Duration of follow-up extended to 32 years (greater than 10 years in 35%). Twenty of the 48 patients (42%) died, 6 in the first week of life and 1 at age 5 months. Thirteen of the 41 patients surviving to age 6 months subsequently died, 50% probability of survival being reached at 47 years. Significant (p less than or equal to 0.05) predictors of death in this group were: male sex, cardiothoracic ratio greater than or equal to 0.65, New York Heart Association class III or IV, breathlessness and the absence of Wolff-Parkinson-White syndrome. Eight patients died suddenly. A cardiothoracic ratio greater than or equal to 0.65 was a better predictor of sudden death than functional status. All who developed atrial fibrillation died within 5 years. Other atrial arrhythmias were not helpful in predicting sudden death. In view of these findings, tricuspid valve surgery is recommended before the cardiothoracic ratio reaches 0.65, regardless of the symptomatic state.