This Issue Brief reports on changes in manufacturers' prescription drug prices during the first three months of 2004 (January through March) for the brand name prescription drugs most widely used by Americans age 50 and over. This report is the first quarterly update in an ongoing study of changes in drug manufacturer prices-that is, manufacturers' prices charged for drugs they sold to wholesalers. A baseline study published in May 2004 by the AARP Public Policy Institute identified steady increases in the average annual manufacturer price from calendar year 2000 through calendar year 2003. This report's focus is on changes in the prices that brand name drug manufacturers charge to wholesalers for sales to retail pharmacies. The manufacturer's charge to wholesalers is the most substantial component of a prescription drug's retail price. When there is an increase in the manufacturer price to wholesalers for a brand name drug, this added cost is generally passed on as a similar percent change in the retail price to most prescription purchasers. The report presents three measures of price change (see methodological appendix). The first set of findings are annual rates of change in manufacturers' prices for widely used brand name drugs, using both rolling average and point-to-point estimates; information is presented on percentage change in manufacturer price and on potential dollar changes in consumer spending. The second set of findings are three-month percentage changes in prices (i.e., changes from December 31, 2003 through March 31, 2004); the distribution of percentage price changes is shown, as well as differences in average percentage price changes by manufacturer and by therapeutic category.