Adverse drug reaction surveillance conducted by the US Federal Food and Drug Administration (FDA) is important for detecting new safety information about pharmaceuticals. FDA has sought to stimulate reporting of reactions by practitioners and manufacturers. Over the five years from 1989 to 1993, reporting more than doubled and a total of 421,491 reports were received. This trend continued in 1994. The origin, type of reaction and drug are presented. Most reports are made by health professionals through pharmaceutical manufacturers. About 5% of such reports involve serious reactions to new drugs. Uses and limitations of ADR surveillance are briefly discussed.