This paper describes the role of databases used for postmarketing surveillance of drugs at the United States Food and Drug Administration (FDA). First we describe the Adverse Event Reporting System (AERS), the largest database of adverse event reports in the world. Next, we explain the methods we have used for assembling these adverse event reports into a case series and analysing them, as well as techniques for employing drug use databases to construct reporting rates in the evaluation of drug safety issues. Finally, we discuss the FDA's use of the databases it accesses through its Cooperative Agreement Program to conduct high priority studies to support regulatory decision-making.