Food and Drug Administration (FDA) review times have significantly declined under the user-fee regime. This situation has provoked concerns that drug safety has been adversely affected. Combining information from several comprehensive databases, we analyze how the FDA's review time, a drug's novelty, and a lag between the foreign and U.S. launches of a drug affect the number of serious adverse events associated with new-drug introductions in the United States in 1992-2002. We find that more novel drugs, those with shorter U.S. launch lags, and those with black-box warnings have a larger number of serious adverse events. After controlling for these and other factors, we find no association between the FDA's review time and adverse events. Because many serious adverse events involve rare occurrences that are not observable in premarket clinical trials, policy makers should direct increased agency attention and resources to postmarketing surveillance.