We describe survival in patients with Down syndrome (DS) with single-ventricle anatomy and palliation and characterize risk factors associated with mortality. All patients with DS and single-ventricle anatomy documented in the electronic medical record at our institution from January 1, 1992, to May 1, 2014, were compared with patients with unbalanced atrioventricular septal defects and single-ventricle anatomy, without DS or heterotaxy, during the same period. Survival analysis was performed to evaluate factors associated with mortality, including the presence of DS. There were 28 patients with DS and 30 patients without DS. One-year survival with DS was 75% (95% CI: 55% to 87%); 5-year survival was 61% (95% CI: 40% to 76%). All DS deaths except one occurred before 2 years of age. One-year non-DS survival was 93% (95% CI: 76% to 98%); 5-year survival was 85% (95% CI: 64% to 94%). Factors associated with death by univariable analysis included DS (p= 0.04), pulmonary vascular resistance (PVR) of at least 3 Wood units× meter(2) (WUm(2)) in the first year of life (p= 0.03), and moderate-to-severe atrioventricular valve regurgitation (p= 0.1). In combined analysis, when accounting for PVR of at least 3 WUm(2) (hazard ratio [HR] 9.8, 95% CI: 1.1 to 83.5, p= 0.04), DS was not associated with increased mortality (HR1.5, 95% CI: 0.3 to 7.8, p= 0.66). No patient with DS with PVR less than 3 WUm(2) died. Children with DS and single-ventricle anatomy have excellent survival when PVR is less than 3 WUm(2) in the first year of life, with minimal mortality beyond 2 years of age. When accounting for PVR, DS alone is not associated with increased mortality in patients with single-ventricle anatomy.