OBJECTIVES: Two national evidence-based guidelines recommend initiation of erythropoiesis stimulating proteins (ESPs) in chemotherapy-induced anemia (CIA) at hemoglobin (Hb) levels of °Ü10 g/dL per ASH/ASCO guideline (2002) and <11g/dL per NCCN guideline (1998), and maintenance of Hb near but not over 12 g/dL. The extent to which these guidelines are followed in actual practice is unknown. This retrospective study examined the patterns of ESP use in cancer patients with CIA. METHODS: The Varian Medical Oncology database of electronic medical records (EMRs) from 17 outpatient oncology practices in the US was utilized. Adults with a malignant tumor diagnosis between January 1, 2004 and July 27, 2006 who received at least one cycle of chemotherapy were studied. The proportion of patients receiving ESPs was calculated by chemotherapy cycle, Hb level during each cycle, and year. RESULTS: A total of 13,069 cancer patients were studied. Median age was 61 years, 60% were female, 38% had ECOG PS 0-2, and 30% had metastases. Forty-four percent had solid malignant tumors of which breast, lung and colorectal cancer were most common. Lymphoma was the most common hematologic cancer. The percentages of patients receiving ESPs during the initial cycle of the first planned chemotherapy regimen were 46.1%, 48.9%, and 48.2% at Hb °Ü10 g/dL; 44.5%, 52.7%, and 51.4% at Hb level of >10 to <11 g/dL, in years 2004, 2005, and the first 10 months of 2006 respectively. Across all years, the proportion of patients receiving ESPs at Hb < 11 g/dL was 49.1%. Few patients (2.6-4.1%) with Hb °Ý 12 g/dL received ESPs. CONCLUSION: ESP use changed little over time. The overall proportion was under 50% in patients with Hb < 11 g/dL, the guideline-recommended range for ESP initiation. Further research is needed to understand the reasons for apparent under-utilization of ESPs in community oncology practices.