Background: Only 1 in 3 eligible Veterans receives an aldosterone antagonist (AA) after HF hospitalization. Our objective was to characterize the patient characteristics associated with appropriate AA prescription. Methods: From the VA External Peer Review Program, we identified a nationwide sample of Veterans with preexisting HF who were discharged from a VA hospital with a principal diagnosis of HF from 10/02 to 07/09. Patients were considered eligible for AA if they had LVEF ≤ 40%, serum creatinine ≤ 2.5 mg/dL for men/≤ 2.0 for women, serum potassium ≤ 5.0 meq/L, and were prescribed a beta-blocker or ACE-inhibitor or ARB at discharge. Patient demographics, vital signs, medications, labs, and coexisting illnesses were compared between patients who filled a prescription for an AA within 90 days of discharge versus those who did not. To examine patient-level predictors of aldosterone blocker fill among eligible patients, we used a generalized estimating equation adjusted for selected covariates to account for within hospital clustering. A backward selection procedure was used for covariate selection with a criterion of p<0.10 for model entry and termination. Results: Of the total cohort (n=14,534), 64% (n=9,355) were eligible for an AA (mean age 70 years, mean serum creatinine 1.4 mg/dL, 70% white, 1% female). Beta-blocker and ACE/ARB use were each > 90%. AA use was significantly associated (p<.05) with younger age, black ethnicity, lower systolic BP, higher body mass index, hospitalization prior to 2008, lower comorbidity score, DM, liver disease, electrolyte disorders, depression, discharge prescription of loop or thiazide diuretics, beta blocker, warfarin, lower serum sodium, lower serum creatinine, and with having no history of metastatic cancer or drug abuse. Age and BP accounted for the greatest percentage of total variability in AA use. Conclusions: Patient characteristics associated with AA prescription were primarily clustered in the domains of age, ethnicity, HF severity-associated variables, potential contraindications, and comorbid conditions. It is unclear whether the association of increasing age with lower AA use is a disparity to be overcome or a safety concern. Certain patient characteristics, not previously reported, were found to be associated with AA use and may partially explain apparent gaps in appropriate use among Veterans.