There are no large population-based studies on the incidence and prognosis of peripartum cardiomyopathy (PC). Between 1996 and 2005, there were 241,497 deliveries within the Southern California Kaiser healthcare system. Among these, we identified 60 cases of PC by searching for an International Classification of Diseases, Ninth Edition diagnosis of heart failure (HF) and detailed chart review. PC was confirmed if all of the following criteria were satisfied: (1) left ventricular ejection fraction <0.50, (2) met the Framingham criteria for HF, (3) new symptoms of HF or initial echocardiographic diagnosis of left ventricular dysfunction occurred in the month before or in the 5 months after delivery, and (4) no alternative cause of HF could be identified. The overall incidence of PC was 1 in 4,025 deliveries. The incidence in whites, African-Americans, Hispanics, and Asians was 1 of 4,075, 1 of 1,421, 1 of 9,861, and 1 of 2,675 deliveries, respectively. The incidence of PC was greatest in African-Americans, which was 2.9-fold higher compared with whites (p = 0.03) and 7-fold that of Hispanics (p <0.001). With a mean follow-up of 4.7 years, the freedom from all-cause death was 96.7% by the Kaplan-Meier method. In conclusion, this large population-based study highlights important racial differences in the incidence of PC. We observed the lowest incidence of PC in Hispanics and the highest in African-Americans. Our findings also suggest that the current mortality associated with PC may be less than reported in older series, perhaps because of the high utilization of modern HF therapy.