The sharp rise in drug abuse in the past decade has led to the development of new sources of information on drug-abuse trends. These include surveys, drug-related emergencies, drug-abuse treatment, hepatitis rates, and various types of law enforcement information. This paper summarizes data currently available for heroin, marijuana, cocaine, amphetamines, and barbiturates. Heroin use occurred in epidemic form in the late 1960s. Some cities, which had experienced a subsequent decline in heroin use, recently have reported an increase again. Marijuana use has increased steadily. The abuse of amphetamines and barbiturates appears to be growing. Trends on cocaine use are unclear. The development of ongoing, quantitative data-collection systems is beginning to clarify many of the issues regarding drug-use patterns and trends. With the possible exception of survey data, however, each indicator provides data only on selected segments of the drug-using population.