Introduction. A wide range of fungi and medicinal herbs, rich in hallucinogenic substances and widely used for mystic and medicinal purposes, can give rise to neurotoxic symptoms. Development. We review the toxic syndromes that can arise from the ingestion of hallucinogenic fungi, cacti and plants, together with descriptions of cases of acute poisoning resulting from the use of medicinal herbs and from foodstuffs that are contaminated by mycotoxins. A series of different psychedelic fungi belonging to the Psilocybe, Panacolus and Stropharia genera contain hallucinogenic alkaloids such as psilocybin. Some of the most notable plants displaying hallucinogenic and sedative properties are Papaver somniferum, Erytroxylum sp. and Cannabis sativa. Infusions of ayahuasca are obtained from the lianas and roots of different plants with psychoactive properties, such as Banisteriopsis caapi and Psychotria viridis, which contain alkaloids derived from tryptamine and from the beta-carboline harmala. Peyote, a cactus rich in mescaline, and Claviceps purpurea (a fungus rich in LSD) are strong hallucinogens. We also examine ergotism and mycotoxicosis from Arthrinium sp. Poisoning from mycotoxin-containing moulds on sugar cane can give rise to encephalopathy and late dystonia. Some of the more noteworthy medicinal plants for which neurological toxicity has been reported are Hypericum perforatum, kava-kava (Piper methysticum), Aconitum sp. and Callilepis laureola. Conclusions. Because of the increasingly more widespread consumption of herbs and fungi and their potentially neurotoxic effects, in clinical practice there is a need to be aware of the neurological syndromes deriving from their use.