In 2005 the new disciplině of addictology came into existence. It is based on a so-called multidisciplinary approach to substance use and its causes, context and impact. Addictive substances pose significant health, sociál, legal and economic risks for both society and individuals. Since 1989 many changes in substance use háve oceurred. The consumption of legal addictive substances (such as aleohol and tobacco) has shown a continuously inereasing tendency. The drug scene involving illicit substances has seen dramatic changes which háve resulted in the virtual extinction of its previous nature and the rise of a drug scene operating on a commercial basis, which is a pattern we know from the Western European countries. The authors of this páper summarize current basic data reflecting the use of both types of addictive substances and point out that the so-called reereational users are the group which is the least covered by research although, statisti-cally, it is the largest group of users. A major proportion of this group nevěr becomes directly engaged with treatment programmes or serveš a prison sentence, and, in terms of public health, insufficient attention has been paid to this group.

        Key words: Legal substances, illicit substances, use, epidemiologie indicators, addictology.