The transition to Medicare's new prospective payment system for hospital outpatient services has arguable been the most complex and difficult programmatic change in the history of Medicare (Federal Register, 2002). Concern about its adverse effects led to holding rural hospitals with 100 beds or fewer harmless from the financial consequences of the new payment system for the first three years. However, small rural hospitals were not held harmless from implementing the outpatient prospective payment system (OPPS). Many outside observers felt that small rural hospitals would be ill-equipped to handle the immensity of change required, and that claim denials or delays caused by inaccurate claims submissions might have a disproportionate effect on smaller hospitals. There were also reports about difficulties with the interim payment system that had been designed to ensure small hospitals did not lose money during the first three years. This policy brief describes issues that arose in implementing OPPS during the first years of the program, identifies specific implementation concerns for small rural hospitals, and raises issues that may warrant further research or policy action.