After an interruption of almost 20 years, psychopharmacological research on hallucinogenic drugs was revived in several countries simultaneously around 1990. Most of the projects that have been initiated since then have been based on the conception of model psychosis: by administering hallucinogens to healthy test subjects, psychiatrists induce a state regarded as an artificial and temporary psychosis, which can be studied under controlled experimental conditions in the laboratory. As a model of psychosis, the hallucinogen intoxication is meant to provide important clues to schizophrenia research. This article examines the history of the concept and practice of model psychosis in order to demarcate the peculiarities of its most recent articulation in the vocabulary of cognitive neuroscience. It highlights the shift from phenomenological to biological psychiatry. The analysis contributes to an understanding of the ‘regional epistemology’ of psychopharmacology by reflecting on the question: what kind of a model is the hallucinogen model of psychosis?