OBJECTIVES:  The Medicare Prescription Drug, Improvement and Modernization Act of 2003 (MMA) changed reimbursement of outpatient drugs reimbursed under Medicare Part B from 95% of average wholesale price to 106% of the average sales price as a cost saving measure. Shortly thereafter many commercial payers followed suit.  This analysis examines the impact of the change in the reimbursement schedules on actual payments provided to physicians for administrations of 5 high cost Part B reimbursed oncology drugs. METHODS:    Using the MarketScan Research Databases ©, claims for administrations of pemetrexed, bevacizumab, trastuzumab, rituximab, docetaxel, and zoledronic acid were identified from January 1, 2004 through December 31, 2011 among cancer patients with non-capitated commercial or employer-sponsored supplemental Medicare insurance.  Claims were excluded from the payment analysis if the reimbursed amount was less than $100 to omit use for other indications, such as the use of bevacizumab for treatment of macular degeneration.  Median reimbursed amounts, encompassing both plan and patient paid amounts, were reported by year, after adjusting to 2011 dollars using the consumer price index.  Compound annual growth rates (CAGRs) between 2004 and 2011 were computed to assess the change in reimbursements over time.     RESULTS:   A total of 1.98M Commercial and 839k Medicare claims were analyzed.  Negative CAGRs between 2004-2011 were observed in only two of the therapies: pemetrexed (-11% CAGR in Commercial population) and zoledronic acid (-2 % to -3% in the Medicare and Commercial population, respectively). The remaining oncology Part B therapies exhibited CAGRs of 1-5%, with the exception of trastuzumab which had 11-13% growth.  CONCLUSIONS:   The amount reimbursed for several key oncology therapies administered in providers offices did not shift dramatically downward after the implementation of MMA.  Further research will examine shifts in dosage levels, frequency, and location of administrations (office vs. hospital) to determine the drivers of the upward shift in average reimbursed amount per claim.