Designer drugs belong to a group of legally or illegally produced substances that are structurally and pharmacologically very similar to illicit drugs. In the past, designer drugs were often used during all-night dance parties, but they are now consumed in multiple settings from college bars to parks to private house parties. Most of these club drugs can be bought on legal websites and home-delivered for private parties. Recently, legal highs have once again become a burning media issue across the world. Our review will focus on GHB and synthetic cathinones. Literature searches were conducted for the period from 1975 to July 2010 using PubMed, EMBASE, PsycInfo, Internet underground and governmental websites using the following keywords alone or in combination: designer drugs, club drugs, party drugs, GHB, synthetic cathinones, mephedrone, methylone, flephedrone, MDAI, and MDVP. Available epidemiological, neurobiological, and clinical data for each compound are described. There is evidence that negative health and social consequences may occur in recreational and chronic users. The addictive potential of designer drugs is not weak. Non-fatal overdoses and deaths related to GHB/GBL or synthetic cathinones have been reported. Clinicians must be careful with GBL or synthetic cathinones, which are being sold and used as substitutes for GHB and MDMA, respectively. Interventions for drug prevention and harm reduction in response to the use of these drugs should be implemented on the Internet and in recreational settings. Prevention, Information, Action, and Treatment are the main goals that must be addressed for this new potentially addictive problem.