Clinical, angiographic, radiographic, and echocardiographic data on 46 neonates with Ebstein's anomaly presenting with cyanosis between 1954 and 1996 were reviewed to determine possible risk factors for mortality. Most patients (67%) presented at birth with 3 cases diagnosed in utero. Mean systemic oxygen saturation was 62+/-12%. An atrial septal defect > or = 4 mm was noted in 20 patients (44%). The patent right ventricle to pulmonary artery connection was present in 10 (22%), and pulmonary atresia was functional in 25 (54%) and anatomic in 11 patients (24%). Fifteen patients (35%) underwent surgical interventions. Total mortality was 70% (vs 14% in acyanotic patients diagnosed during the same time period; p <0.0001) and was related to low cardiac output and hypoxia in 20 patients (62%), postoperative complications in 8 (25%), and sudden death in 4 (13%). Kaplan-Meier survival estimates were 61% at age 1 week (95% confidence interval [CI], 47% to 75%), 48% at age 1 month (95% CI, 34% to 62%), and 36% at both 1 and 5 years of age (95% CI, 22% to 50%). Mortality improved from 81% in 1954 to 1985 to 47% in 1986 to 1996 (p = 0.04). Significant independent predictors of mortality included an atrial septal defect > or = 4 mm (odds ratio [OR] 2.39; p = 0.04), reduced left ventricular function (OR 4.10; p = 0.002), and functional or anatomic pulmonary atresia (OR 2.44, p = 0.003; and OR 5.97, p = 0.004, respectively). An echocardiographic ratio of the combined right atrial and atrialized right ventricular area to the area of the functional right ventricle and left heart >1.0 was 100% predictive of mortality.