In recent years, a series of new drugs, known as smart drugs or legal highs, have gaining in popularity. They are easily obtainable through online shops. This is happening amongst younger segments of the population and is associated with recreational consumption, at weekends. In general, they are synthetic derivatives of natural products. There has been hardly any clinical research into them and they are not detectable in hospital laboratories. Three of these products, BZP (1- benzylpiperazine), mefedrone (4-methylmethcathinone) and Spice are probably the most widely used in Europe. The first two are consumed as an alternative to ecstasy and cocaine and are characterized by their producing a clinical profile of a sympathetic mimetic type; on occasion, they have serious consequences, with convulsions and even death. Spice (a mixture of herbs with synthetic cannabinoids such as JWH-018, JWH-073 and CP 47497-C8) is giving rise to profiles of dependence and schizophrenia. Although the emergent drugs have an aura of safety, there is an increasing amount of experience on their secondary effects.