[영문]Purpose.Drug expenditure trends in 2007 and 2008, projected drug expenditures for 2009, and factors likely to influence drug expenditures are discussed.Summary.Various factors are likely to influence drug expenditures in 2009, including drugs in development, the diffusion of new drugs, drug safety concerns, generic drugs, Medicare Part D, and changes in the drug supply chain. The increasing availability of important generic drugs and drug safety concerns continue to moderate growth in drug expenditures. The drug supply chain remains dynamic and may influence drug expenditures, particularly in specialized therapeutic areas. Initial data suggest that the Medicare Part D benefit has influenced drug expenditures, but the ultimate impact of the benefit on drug expenditures remains unclear. From 2006 to 2007, total U.S. drug expenditures increased by 4.0%, with total spending rising from