As a competitive adenosine antagonist, caffeine affects dopamine transmission and has been reported to worsen psychosis in people with schizophrenia and to cause psychosis in otherwise healthy people. We report of case of apparent chronic caffeine-induced psychosis characterized by delusions and paranoia in a 47-year-old man with high caffeine intake. The psychosis resolved within 7 weeks after lowering caffeine intake without use of antipsychotic medication. Clinicians might consider the possibility of caffeinism when evaluating chronic psychosis.