Marijuana was found to be the most common illicit drug used by European adolescents. Findings also showed that over the study period there was a significant increase in the number of adolescents who used drugs repeatedly between 1995 and 2003. A similar increase occurred in the use of ecstasy over the same period. Between 1999 and 2003, the use of opiates and amphetamines decreased slightly in the Czech Republic. Regarding drug-related attitudes, Czech adolescents tended to be more tolerant toward selected forms of drug-using behavior than were their peers in other European countries. Efforts to address drug-related health and social issues included an expansion of the network of specialized facilities for treatment and resocialization, as well as long-term programs in prevention. The future will likely see an increase in early detection and intervention. These findings were obtained from a database of the European School Survey on Alcohol and Other Drugs from 1995, 1999, and 2003. At the time of data collection, the average age of respondents in the sample was 15.4 years old. 8 tables, 3 figures, and 17 references