Statistics on drug misusers in the population is valuable for strengthening deterrents tightening domestic controls, and developing prevention and treatment programs. Official notifications of addicts gathered from medical practitioners cannot provide precise estimates of drug abusers. As an alternative, the indicator method has been developed in which research workers use the Addicts Index to count all addicts notified from the area during a specified time period. They also ask all medical, social, and police agencies to inform them of known drug misusers and search coroner's records for drug-related deaths. The paper examiners difficulties with the indicator method, as well as more serious shortcomings in surveys of self-reported drug misuse among samples of the general population. The authors endorse the indicator method as the best approach to regularly monitoring the numbers of problem drug takers in an area. Tables and 15 references.