New psychoactive drugs, so-called legal highs, have gained more and more popularity during the last years. One of the most important groups of these legal high substances are the synthetic phenethylamines that share a common phenethylamine moiety. Based on certain structural characteristics, these synthetic phenethylamines can be divided into further subclasses, among which the synthetic cathinones (‘bath salts’) are particularly noteworthy. Synthetic cathinones are characterized by an additional carbonyl group attached at the beta position on the amino alkyl chain. Consumption of synthetic phenethylamines can lead to impairments similar to those observed after the use of, for instance, amphetamine or 3,4-methylenedioxy-N-methylamphetamine (MDMA, ‘ecstasy’). These impairments include diverse neurological and psychological symptoms which can affect a safe driving behaviour. Although several reports on clinical symptoms and poisonings due to these substances have been published, most of these publications do not contain any analytical data. Additionally, there is still a lack of information concerning pharmacological and toxicological effects of these rather new psychoactive substances. In particular, the knowledge of the impact on the ability to drive following consumption of synthetic phenethylamines is relevant for the police as well as for forensic toxicologists. In this publication, several cases of individuals driving under the influence (DUI) of synthetic phenethylamines (4-fluoroamphetamine, mephedrone (4-methylmethcathinone, 4-MMC), 2-DPMP (desoxypipradol), methylenedioxypyrovalerone (MDPV), benzedrone, N-ethylamphetamine (etilamfetamine), 3-methylmethcathinone (3-MMC)) are presented, focusing on analytical results and signs of impairment.