OBJECTIVE: To evaluate current epoetin alfa (EPO) and darbepoetin alfa (DARB) dosing patterns from 2004-2005 in anemic pre-dialysis chronic kidney disease (CKD) patients receiving care in nephrology clinics. METHODS: A random panel of approximately 250 nephrologists was requested bimonthly to review the medical records of their last two anemic pre-dialysis CKD patients seen who were currently receiving an erythropoiesis-stimulating therapy (EST). Data on patient demographics, co-morbid conditions, CKD status, EST dose, and frequency of administration were collected every 2 months to evaluate changes over time. RESULTS: A total of 943 patient charts were reviewed from November 2004 through September 2005 (EPO: 528; DARB: 415). Patient demographics, comorbid conditions, baseline hemoglobin, and renal function were similar between groups. Weekly and extended (≥Q2W) dosing patterns were seen in both groups (EPO: QW, 47%; Q2W, 32%; Q4W, 15%; Other, 5%; DARB: QW, 23%; Q2W, 41%; Q4W, 33%; Other, 3%). The mean weekly doses over the course of the study (EPO: 10,302 units; DARB: 47 mcg) corresponded to a dose only ratio (units EPO: mcg DARB) of 219:1, resulting in mean weekly costs of $125 and $205 for EPO and DARB (based on 2005 wholesale acquisition costs), respectively. These weekly cost differences were observed in patients both under and over the age of 65. CONCLUSIONS: DARB was associated with a higher mean weekly EST cost compared to EPO. These analyses can guide healthcare providers and decision makers in recognizing real-world dosing patterns and costs of ESTs for the treatment of anemic pre-dialysis CKD patients.