Background-It is not known whether subspecialty care by cardiologists improves outcomes in heart failure patients from the community over care by other physicians. Methods and Results-Using administrative data, we monitored 38 702 consecutive patients with first-time hospitalization for heart failure in Ontario, Canada, between April 1994 and March 1996 and examined differences in processes of care and clinical outcomes between patients attended by physicians of different disciplines. We found that patients attended by cardiologists had lower 1-year risk-adjusted mortality than those attended by general internists, family practitioners, and other physicians (28.5% versus 31.7%, 34.9%, and 35.9%, respectively; all pairwise comparisons, PϽ0.001). The 1-year risk-adjusted composite outcome of death and readmission for heart failure was also lower for the cardiologists compared with family practitioners and other physicians but not general internists (54.7% versus 58.1%, 58.3%, and 55.4%; PϽ0.001, PϽ0.001, and Pϭ0.39, respectively). Multivariable hierarchical modeling demonstrated a significant physician-level effect for both outcomes in favor of the cardiologists, particularly against non-general internists.Cardiologist care was associated with higher adjusted rates of invasive interventions and postdischarge prescriptions of heart failure medications. Conclusions-In this population-based cohort, heart failure patients attended by cardiologists in hospital had lower risk of death as well as the composite risk of death or readmission than patients attended by noncardiologists. These data raise the need to identify specialty-driven differences in processes of care for heart failure patients, which may explain the observed disparity in clinical outcomes that presently favor cardiologist care.