Aims To study the prevalence of cannabis use and drug-related problems among European adolescents and the utility of the prevention paradox. Methods Survey data from the European School Survey Project on Alcohol and Other Drugs (ESPAD) in 2007 in the 27 countries with information about drug use and drug-related problems was used. We analysed the proportion of all drug-related problems that occurred in a high risk group and among others who had used cannabis in the previous 12 months. The cut-off for the high risk group was chosen to include 10-15 % of the most frequent cannabis users. Results The high risk groups accounted for a substantial, but a minority, of drug-related problems among boys as well as girls. A minority of those who had used cannabis reported any drug-related problem. The proportion of adolescents with drug-related problems and the average number of problems increased with frequency of cannabis use. Conclusions We find support for policy measures of more general character, supported by the prevention paradox. However, this does not exclude a policy supporting frequent drug users if they can be identified