&NA;As a test of the hypothesis that neuroleptics can induce a psychosis secondary to dopamine receptor supersensitivity, we examined the behavioral ratings of 20 symptomatic chronic schizophrenic patients who were withdrawn from neuroleptic drugs and maintained drug free for 4 wk. We hypothesized that, if supersensitivity existed, it might be reflected in a drug‐free course characterized by an initial phase of exacerbation followed by improvement (a “hump”). Four patients had such a course. No patient had the inverse of this hypothesized course (improvement followed by relapse). The implications of this finding and problems inherent in testing the supersensitivity psychosis hypothesis are discussed.