Commonly, false peyote refers to Lophophora diffusa. However, several other unrelated cacti go by this colloquial name. They either resemble "true"peyote, Lophophora williamsii, or are found in similar habitats. To date, over 40 different alkaloids have been isolated from the Lophophora genus. Of these, only the pharmacological actions of mescaline (1) have been extensively investigated. The major alkaloid in L. diffusa is pellotine (2), a tetrahydroisoquinoline (THIQ), which was briefly marketed as a sleeping aid around the beginning of the 20th century, following reports of its hypnotic properties in humans. Pharmacological experiments with the Lophophora THIQs were performed at the turn of the 20th century, whereas the chemical synthesis was not realized until several decades later. The biosynthetic pathways of the main Lophophora alkaloids were reported at the end of the 1960s. In this review, the relationship of the different "false peyotes"to L. williamsii, in regard to their alkaloid content, the bio- and chemical synthesis of the most relevant alkaloids, and their corresponding pharmacology will be outlined and discussed.