Introduction. Problems associated with the increasing abuse of plant-derived psychoactive substances have recently attracted attention. This study involved bioanalytical and clinical examinations of intoxication cases suspected to be linked to such plant materials. Methods. Urine samples were collected at emergency wards in Sweden from patients who either admitted or were suspected of ingestion of psychoactive plant materials. The bioanalytical investigation employed a liquid chromatography-tandem mass spectrometry multicomponent method covering 10 plant-derived substances (atropine, dimethyltryptamine, ephedrine, harmaline, harmine, ibogaine, lysergic acid amide, psilocin, scopolamine, and yohimbine) and a gas chromatography-mass spectrometry method for asarone. Routine testing for illicit drugs was also performed. Results. Over a 4-year period, 103 urine samples collected from mainly young people (age range 13-52 years, median 19) were studied. Among 53 cases where ingestion of any of the 11 plant-derived substances covered in this study was admitted or suspected, 41 (77%) could be confirmed bioanalytically. Nine of the 11 substances tested for were detected, the exceptions being ibogaine and yohimbine. Psilocin, originating from ingestion of hallucinogenic mushrooms, was the most frequent drug accounting for 54% of the cases. The most common means of drug acquisition (56%) was purchase over the Internet. Conclusion. The patients using psychoactive plant materials were mainly young and commonly used the Internet for drug acquisition. Having access to bioanalytical methods for detection of plant-derived psychoactives is therefore considered important, when providing clinical toxicology service. © 2009 Informa UK, Ltd.