BACKGROUND: Using data from the Healthcare Cost and Utilization Project 2004 Nationwide Inpatient Sample, we estimated inpatient resource utilization among patients with hematologic malignancies, with and without concomitant acute renal failure. PATIENTS AND METHODS: We analyzed patients with hematologic malignancies (excluding Hodgkin disease), acute renal failure, and renal dialysis. Subgroup analyses were performed on specific types of hematologic malignancies, with and without acute renal failure and with and without renal dialysis. RESULTS: Among those with hematologic malignancies, acute renal failure, with and without concomitant renal dialysis, increases inpatient length of stay and costs. Mean length of stay and costs for all patients with acute renal failure and renal dialysis (n = 5148), acute renal failure without renal dialysis (n = 27,654), and no acute renal failure or renal dialysis (n = 350,601) were 17.6, 12.2, and 7.4 days, and $44,619, $25,638, and $13,947, respectively. CONCLUSION: Treatment of hematologic malignancies and concomitant acute renal failure and renal dialysis places an economic burden on the health care system. Reducing the incidence of acute renal failure and concomitant renal dialysis with supportive care in patients with hematologic malignancies can reduce inpatient resource use.