Background: Patients with coexistent heart failure and chronic kidney disease (CKD) have a poor prognosis, possibly related to the underuse of standard medical therapies-angiotensin-converting enzyme inhibitors (ACE-I) and angiotensin receptor blockers (ARB). Methods: We performed a retrospective analysis of the Minnesota Heart Survey, identifying patients hospitalized in 2000 in the Minneapolis-St Paul metropolitan area with heart failure. The main outcome measure was the association of ACE-I and ARB use on 30-day and 1-year mortality, stratified by glomerular filtration rate (GFR). Results: Compared to patients with heart failure with preserved renal function (GFR ≥90 mL/min), patients with severely impaired renal function (GFR <15 mL/min) were far less likely to receive ACE-I or ARB during hospitalization (52.0% vs 69.5%, P < .0001) or at discharge (50.5% vs 65.1%, P < .0001). Worsening renal function was associated with increased mortality, both at 30 days and at 1 year. The inhospital use of either an ACE-I or ARB was associated with significantly reduced 30-day mortality (OR 0.45, 95% CI 0.28-0.59) after adjusting for multiple risk factors. Similarly, the discharge prescription of either an ACE-I or ARB was associated with a significant reduction in adjusted 1-year mortality (OR 0.72, 95% CI 0.58-0.91). However, among patients on dialysis, there was no benefit of ACE-I or ARB on either 30-day or 1-year mortality. Conclusions: Angiotensin-converting enzyme inhibitors and ARB are underused in patients with heart failure with chronic kidney disease. Given the reduction in 30-day and 1-year mortality, these medications should be considered in most patients with heart failure, independent of underlying renal function. Among patients on hemodialysis, further investigation is warranted.