OBJECTIVES: To compare erythropoiesis-stimulating agent (ESA) dosing patterns and costs in inpatients with chronic kidney disease (CKD) not on dialysis or with chemotherapy-induced anemia (CIA). METHODS: Electronic records from the Premier Perspective Comparative Hospital Database (2006Q1-2009Q4) were analyzed to identify inpatients ≥18 years old treated with epoetin alfa (EPO) or darbepoetin alfa (DARB). Patients receiving renal dialysis or treated with both ESAs were excluded. CKD patients had ≥1 claim for CKD, no claim for cancer, and did not receive chemotherapy. CIA patients had ≥1 claim for cancer, received chemotherapy, and had no claim for CKD. The mean cumulative ESA dose was used to calculate costs, based on April 2010 wholesale acquisition costs (EPO: $15.15/1,000 Units, DARB: $4.96/mcg). RESULTS: A total of 148,746 CKD (EPO: 116,017; DARB: 32,729) and 13,832 CIA (EPO: 10,454; DARB: 3,378) patients were identified. EPO patients were slightly younger than DARB patients in the CKD group (years: 71.0 vs. 71.2; P=.0199) and slightly older in the CIA group (years: 60.7 vs. 59.2; P<.0001). The proportion of females was higher in CKD (EPO 52.3% vs. DARB 51.3%; P=.0018) and similar in CIA (EPO 52.9% vs. DARB 53.8%; P= .3722). The mean length of stay (LOS) was slightly longer for EPO patients (days: CKD: 9.9 vs. 9.7, P=.0006; CIA: 13.4 vs. 12.6; P=.0028). The mean cumulative dose was EPO 37,333 Units and DARB 149 mcg for CKD patients, and EPO 62,605 Units and DARB 272 mcg for CIA patients, yielding dose ratios of 251:1 and 230:1 (Units EPO:mcg DARB), respectively. Corresponding ESA costs were higher for DARB than for EPO in both populations (CKD: $739 vs. $566; CIA: $1,349 vs. $948). CONCLUSIONS: This analysis reported dose ratios of 251:1 and 230:1 and a cost premium associated with DARB of 31% and 42% for CKD and CIA inpatients, respectively, despite longer LOS for EPO patients.