The aim of this study was to evaluate the performance of an adjusted HeartMate II risk score (HMRS) in Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS; n = 9,733) and in HeartWare Ventricular Assist Device (HVAD) bridge to transplant (BTT) trial patients (n = 360). Interagency Registry for Mechanically Assisted Circulatory Support data were used to calculate an adjusted HMRS, omitting center volume, for all patients on continuous-flow left ventricular assist device (LVAD) support. Ninety day mortality was then evaluated in INTERMACS and HVAD-BTT patients. Four risk groups were identified based on INTERMACS patient-adjusted HMRS: very low (<5%, 90 day mortality; score <0.20), low (5-10%, 90 day mortality; score 0.20-1.97), medium (10-20%, 90 day mortality; score 1.98-4.48), and high risk (>20%, 90 day mortality; score >4.48). Within INTERMACS, there were significant differences in survival between all-adjusted HMRS risk groups (p < 0.001 in pairwise comparisons). Controlling for known mortality correlates, the adjusted HMRS mortality hazard ratio was 1.19 (1.25-1.23) per unit HMRS increase. The HVAD cohort was a low-risk cohort with 90 day survivals for very low-, low-, and medium-risk patients of 100%, 97 ± 1.1%, and 90 ± 3.6%, respectively (p = 0.007). Patients in the very low- and low-risk group had significantly improved survival compared with medium-risk patients, respectively (both p < 0.05). The adjusted HMRS appropriately risk stratified a large cohort of INTERMACS patients and was predictive of survival in HeartWare-supported patients.