OBJECTIVES:   Acute heart failure (AHF) is a mounting problem worldwide, with significant economic burden. Renal impairment is common among patients with AHF but its full economic implications are unknown. The study aims to describe and compare medical resource utilization and costs among AHF patients with and without renal impairment. METHODS: Patients with ≥1 hospitalization with a primary diagnosis of AHF continuously enrolled for ≥6 months of baseline period prior to the first hospitalization (FH) were identified in the US MarketScan claims database (2004-2008). History of renal impairment was identified using ICD-9 codes at baseline or FH. Patients were observed for 12 months post FH or until insurance disenrollment. Measured outcomes include inpatient resource utilization, hospital length of stay (LOS) and costs. Rates of hospital re-admissions, outpatient visits and costs were calculated per patient per month (PPPM). RESULTS: A total of 6396 AHF patients (mean age 73.6 years, 50.6% female) were studied; 1082 (17%) had renal impairment. At FH, renal patients had more comorbidities, longer LOS (7.0 vs. 7.9 days), and similar costs ($15,820 vs. $15,467) compared to non-renal patients. The average cost per re-hospitalization was $17,887 vs. $16,780 for renal vs. non-renal patients, with average LOS of 7.9 and 6.5 days, respectively. Throughout the study period, re-hospitalization, outpatient visit rates and costs PPPM were significantly (P<0.05) higher among renal compared to non-renal patients, with highest costs and rates observed within 3 months of FH ($2,480 vs. $1,421 total healthcare cost PPPM; 0.063 vs. 0.024 re-hospitalization PPPM and; 1.406 vs. 1.051 outpatient visits PPPM). CONCLUSIONS: AHF patients with renal impairment are resource intensive and a costly subgroup of AHF population. Their increased use of outpatient services despite having longer, more frequent hospitalizations suggest an unmet need thus, new therapies that reduce re-hospitalizations may offer meaningful cost savings and improved health outcomes.