Since drugs are provided through illegal markets, it is natural to want to track data series pertaining to prices as well as more traditional indicators of demand, use, and quantities consumed. This report continues a series produced by the Office of National Drug Control Policy (ONDCP) and attempts to improve the understanding of trends in prices and purity for five major illicit drugs: powder cocaine, crack cocaine, heroin, d-methamphetamine, and marijuana in the United States from 1981 through the second quarter of 2003, using data from the Drug Enforcement Administration’s (DEA) System to Retrieve Information from Drug Evidence (STRIDE) database. The report is divided into two major sections: (1) results of the price and expected purity of the five specific drugs and (2) the purity of drugs once seized. The results of illicit drug prices indicate that they are still extraordinarily high per unit weight. This is even though prices have declined over the past 20 years. In addition, drug prices have extreme variability over quantity levels, between locations, over time, and from transaction to transaction. Prices also vary substantially over time. The overall trend for powder cocaine, crack, and heroin shows a steep decline during the 1980's, a spike in prices in 1989 through 1990, then relatively stable with a modest decline during the 1990's and early 2000's. Trends and variation in purity are drug-specific but are also quite common. Cocaine purities are now typically fairly high at all quantity levels, and heroin is much more pure than it was in the early 1980's. Additional research is recommended in focusing, not only on further refining and updating of descriptive trends, but also on correlating the trends with other data indicators. Tables and figures