This report analyzes the product liability litigation that occurred in federal district courts from mid-1973 through mid-1986. It attempts to clarify the debate over whether product liability litigation has involved thousands of companies and products and therefore damaged U.S. business, or whether such litigation has consisted primarily of "epidemics" of suits limited to a few products and affecting only a few businesses. It considers how many companies have been involved in federal product liability litigation and to which industry groups they belong; and it examines the patterns exhibited by federal product liability filings since the mid-1970s. The most important general conclusion is that there is significant diversity among defendants, among industries, and even within industries. In particular, a distinction must be drawn between the tiny number of defendants named in thousands of suits, and the thousands of defendants named only once or twice. Policy and law developed to deal with the situation must recognize that an approach that seems suitable for one facet of litigation may be inappropriate for another.