The review contains state-of-the-art knowledge of factors that influence drug-seeking behavior in laboratory animals, including drug vulnerability, basic neurochemical mechanisms, neuronal sites of the "reward" pathway, toxicology, perinatal consequences, and cardiovascular actions. Consideration is given to pharmacological effects of cocaine, cocaine receptors, sensitization to cocaine, behavioral aspects of the reinforcing properties of cocaine, and genetic differences in responses to cocaine. The seriousness of cocaine use in the United States is illustrated by 1985 population statistics that indicate an estimated 22 million persons had at least tried cocaine. The popularity of cocaine is underscored by figures on teenage use; over half of 1987 high school graduates had tried illicit drugs at least once, and slightly over 15 percent had used cocaine. Cocaine produces a number of physiological effects, including psychomotor stimulation, hypertension, tachycardia, anorexia, pupillary dilation, and euphoria. These effects are related to the two major actions of cocaine, local anesthesia effect and action on the central nervous system. References, tables, and figures.