The prevalence of known cases of drug use was studied on the basis of data on drug use, where 9,689 individuals were identified (8,821 males and 868 females) in 51 counties of Greece from 1973-1983. The mean age was 38.7 for male and 31.2 for female drug users. Of the drugs, cannabis resin was the drug used most often by males, and heroin and other opiates by females. The general population survey carried out in 1984 was based on a household interview of 4,292 individuals randomly selected in a sample that covered the population aged 12-64 years. The findings show that at some time in their lives 5.5 percent of the respondents (9.1 percent of the males and 2.5 per cent of the females) used illicit drugs, and 11.1 percent (6.5 percent of the males and 14.9 percent of the females), licit drugs. Cannabis resin was the illicit drug most often used by both males and females. Minor tranquilizers were the licit drugs most often used. The results of this research will hopefully offer basic information for the planning of measures to prevent and reduce drug abuse in Greece. 15 references. (Author abstract modified)