Recent revelations of unexpected side effects of widely prescribed medications have raised questions about several aspects of U.S. drug policy, from initial Food and Drug Administration (FDA) approval to promotion by manufacturers and prescribing by physicians. One prominent example is nesiritide (Natrecor), a treatment for congestive heart failure. We use it as a case study to assess how FDA standards for drug approval, marketing practices by drug manufacturers, and physicians' prescribing choices can shape the risk-benefit relationship of new drugs. Based on the nesiritide experience, we suggest several ways to improve policies for drug approval, postmarketing surveillance, and drug utilization.