This is the fourth in a series of compendia on drug side effects and adverse reactions. The book represents a massive effort, containing 28 chapters contributed by 39 scientists from around the world. The first 12 chapters are devoted to epidemiology and mechanisms of adverse drug reactions. Four articles discuss genetic aspects of drug reactions, carcinogenesis, teratogenesis, and chromosomal aberrations; these chapters illustrate the paucity of adequate epidemiologic data in humans and the difficulties in interpreting anecdotal reports. Drs. Ariens and Simonis from the University of Nijmegen contribute a superb review of classification and mechanisms of drug reactions. Microsomal enzyme induction (Drs. Conney and Gelboin) is the subject of another excellent paper. Unfortunately, the chapter on approaches to monitoring drug use and assessing reports of adverse reactions—perhaps the most important of the book—is weak. Crucial differences between spontaneous reporting systems and intensive hospital-based monitoring programs are superficially discussed. Chapters 12