OBJECTIVES: Increasing prevalence of heart failure (HF), increasing enrollment in state programs, sparse literatures on population-based heart failure studies, and the burden of hospitalization among Medicaid patients necessitate an analysis of risk factors for heart failure hospitalization in a contemporary Medicaid population. METHODS: Claims from Maryland State Medicaid, for 14,149 non-dually enrolled, 18-64 year olds with a diagnosis for HF between 7/1/05-12/31/09, followed for at least six months. We examine the effects of comorbidity and first-line therapy use on the risk of any hospitalization after HF diagnosis. Multivariate Weighted Cox Regressions were used to address non-proportional risk of hospitalization over the follow-up period.  We report numbers needed to treat with first-line therapy to prevent one hospitalization annually. RESULTS: Most patients were >45 years (71%), female (56%), and black (60%). Use prevalence was: beta-blockers (26%), ACE-inhibitors/ARB (29%), aldosterone antagonists (AA, 5%), and others including nitrates+hydralazine (37%). Nearly all (98%) were diagnosed with one or more comorbidities. Relative risk (95% CI) for any hospitalization was 1.43 (1.36-1.51) renal dysfunction, 1.40 (1.31-1.50) other cardiovascular, 1.33 (1.26-1.40) COPD, 1.28 (1.22-1.35) chronic ischemic heart disease, 1.27 (1.20-1.34) stroke, 1.26 (1.20-1.32) diabetes, 1.11 (1.05-1.17) hypertension, 0.81 (0.77-0.85) hyperlipidemia, 0.77 (0.73-0.81) psychological disorder; 0.77 (0.73-0.81) ACE inhibitor/ARB, 0.83 (0.79-0.87) beta-blocker, 0.76 (0.72-0.80) other cardiovascular drugs. AA and/or nitrates+hydralazine combination had no impact. The C-statistic for predicted 1-year hospitalization risk within the sample was 0.80. Numbers needed to treat to prevent one hospitalization annually: 12 ACE-inhibitor/ARB, 15 beta-blockers, or 11 other cardiovascular drugs.  CONCLUSIONS: We elicit the specific risk attributable to lead risk factors in HF patients enrolled in Medicaid plans, and show certain disease modifying therapies can quantifiably mitigate risk of hospitalization. Growing ranks of state Medicaid plans and other entitlement programs call for more deliberate, proactive and cost-effective disease and risk management of plan enrollees.