In the past decade, there has been a significant increase in the popularity of synthetic cathinones in the illegal drug market. They have been easily available from Internet-based vendors as well as at "head shops" and "smart shops." The recent prominence of synthetic cathinones can be attributed to their stimulatory properties similar to those of amphetamines. This paper provides a review on the current popular cathinone derivatives, their history and prevalence in the illegal drug market, legislation of these drugs in various countries, pharmacology, toxicology, and metabolism studies, analysis of toxicology samples (blood, urine, and hair) and criminalistic samples (seized, purchased via the Internet, and synthesized). From the reviewed literature, it is concluded that the products sold as "legal highs" do not only contain cathinone, but also cathinone derivatives, and adulterants such as caffeine, lidocaine, and in organic materials. Full toxicity data are currently unavailable for this drug class and hence more research is required with regard to their analysis and metabolism. Moreover, clandestine chemists are constantly synthesizing new derivatives and hence forensic chemists often need to synthesize and characterize these drugs to confirm the identity of the seized samples. This is expensive as well as time consuming; therefore, there is a need for national and international collaboration among forensic chemists to overcome this difficulty. (Published Abstract)