OBJECTIVES: This retrospective claims analysis aimed to compare erythropoiesis-stimulating agent (ESA) dosing patterns and costs in chemotherapy-induced anemia (CIA) hospital outpatients. METHODS: Electronic records from the Premier hospital database (2006Q1-2011Q1) were used to identify outpatients aged ≥18 years that had a diagnosis for cancer, received chemotherapy during hospitalization, and received epoetin alfa (EPO) or darbepoetin alfa (DARB).Exclusion criteria were: a diagnosis of chronic kidney disease, diagnosis of myelodysplastic syndrome, receipt of renal dialysis, or receipt of both ESAs. The observation period consisted of the outpatient continuous ESA episode, defined as the period from first to last outpatient visit with ESA use without a gap of more than one calendar month between ESA visits. The ESA dose ratio (Units EPO: mcg DARB) was calculated using the mean cumulative dose of EPO and DARB. ESA treatment costs were determined using cumulative dose and December 2010 wholesale acquisition costs.  RESULTS: A total of 7413 outpatient ESA episodes (EPO: 3979; DARB: 3434) were identified.  The EPO group had a lower proportion of females versus the DARB group (61.7% vs. 67.7%, respectively; P<0.001), however, EPO and DARB groups had a similar mean age (62.0 vs. 61.8 years, respectively; P=0.560) and duration of outpatient episode (2.3 months for both, P=0.738).  The mean cumulative dose was EPO 212,752 Units and DARB 998 mcg, resulting in a dose ratio (Units EPO: mcg DARB) of 213:1. Corresponding mean ESA treatment costs were higher for DARB than for EPO (EPO: $3,223 vs. DARB: $5,352, P<0.001). CONCLUSIONS: In this analysis of CIA hospital outpatient records, a dose ratio (Units EPO: mcg DARB) of 213:1 was observed.  Mean ESA treatment costs were observed to be approximately 66% higher for the DARB group than for the EPO group.