New patterns of drug abuse have rapidly appeared in the Western world since the Second World War. These patterns are characterized by the rapid introduction and spread of manufactured substances adopted from medicine. Interest has been sustained among illicit users by the search for new mood altering drugs. Both recreational use and multiple drug patterns are becoming increasingly predominant. Western youth has taken the forefront in the new patterns, especially in the rise of marijuana. Sex differentials are rapidly decreasing as more females are smoking. In the United States, hallucinogens have also been abused in large amounts. This reveals an important difference from Europe, where hallucinogen abuse has been low, but amphetamine abuse has been as high or higher than in the United States. Spread has been rapid throughout the populations studied, both from the colleges to the secondary schools, and from country to country, based on current rapid methods of communication and transportation. These data are important in formulating hypotheses for study and control of both epidemic and endemic drug abuse.