Drug testing is a harm reduction strategy that has been adopted by certain countries in Europe. Drug users are able to hand in their drugs voluntarily for chemical analysis of composition and dose. Drug users will be alerted about dangerous test results by the drug testing systems directly and through warning campaigns. An international collaborative effort was launched to combine data of drug testing systems, called the Trans European Drug Information (TEDI) project. Drug testing systems of Spain, Switzerland, Belgium, Austria, Portugal, and the Netherlands participated in this project. This study presents results of some of the main illicit drugs encountered: cocaine, ecstasy and amphetamine and also comments on new psychoactive substances (NPS) detected between 2008 and 2013. A total of 45 859 different drug samples were analyzed by TEDI. The drug markets of the distinct European areas showed similarities, but also some interesting differences. For instance, purity of cocaine and amphetamine powders was generally low in Austria, whilst high in Spain and the Netherlands. And the market for ecstasy showed a contrast: whereas in the Netherlands and Switzerland there was predominantly a market for ecstasy tablets, in Portugal and Spain MDMA (3,4-methylenedioxymethamphetamine) crystals were much more prevalent. Also, some NPS appearing in ecstasy seemed more specific for one country than another. In general, prevalence of NPS clearly increased between 2008 and 2013. Drug testing can be used to generate a global picture of drug markets and provides information about the pharmacological contents of drugs for the population at risk. Copyright © 2016 John Wiley & Sons, Ltd.