OBJECTIVES: This study aimed to examine the role of nutrition in pediatric dilated cardiomyopathy (DCM). BACKGROUND: In adults with DCM, malnutrition is associated with mortality, whereas obesity is associated with survival. METHODS: The National Heart, Lung, and Blood Institute-funded Pediatric Cardiomyopathy Registry was used to identify patients with DCM and categorized by anthropometric measurements: malnourished (MN) (body mass index [BMI] <5% for age >/=2 years or weight-for-length <5% for <2 years), obesity (BMI >95% for age >/=2 years or weight-for-length >95% for <2 years), or normal bodyweight (NB). Of 904 patients with DCM, 23.7% (n = 214) were MN, 13.3% (n=120) were obese, and 63.1% (n=570) were NB. RESULTS: Obese patients were older (9.0 vs. 5.7 years for NB; p < 0.001) and more likely to have a family history of DCM (36.1% vs. 23.5% for NB; p = 0.023). MN patients were younger (2.7 years vs. 5.7 years for NB; p < 0.001) and more likely to have heart failure (79.9% vs. 69.7% for NB; p = 0.012), cardiac dimension z-scores >2, and higher ventricular mass compared with NB. In multivariable analysis, MN was associated with increased risk of death (hazard ratio [HR]: 2.06; 95% confidence interval [CI]: 1.66 to 3.65; p < 0.001); whereas obesity was not (HR: 1.49; 95% CI: 0.72 to 3.08). Competing outcomes analysis demonstrated increased risk of mortality for MN compared with NB (p = 0.03), but no difference in transplant rate (p = 0.159). CONCLUSIONS: Malnutrition is associated with increased mortality and other unfavorable echocardiographic and clinical outcomes compared with those of NB. The same effect of obesity on survival was not observed. Further studies are needed investigating the long-term impact of abnormal anthropometric measurements on outcomes in pediatric DCM. (Pediatric Cardiomyopathy Registry; NCT00005391).