In 2007, the pharmaceutical industry spent more than $4.9 billion on direct-to-consumer advertising (DTCA) of prescription drugs in the U.S. Controversy over DTCA has grown since the Food and Drug Administration liberalized its regulations in 1997. Proponents claim that such advertising educates consumers, promotes patient participation in clinical decisions, and improves patient adherence to medication instructions. Opponents argue that such advertising is meant to persuade, not educate, and that it promotes inappropriate use of prescription drugs, or diverts consumers from better alternatives. This Issue Brief summarizes the evidence about the effects of DTCA, and proposes guidelines for improving the utility of prescription drug advertising.