OBJECTIVE The aim of this study was to determine whether acutely psychotic first-episode schizophrenics show an increased cerebral blood flow velocity and whether this condition is reversible on psychopathological improvement. METHODS In the first of two examinations, transcranial Doppler ultrasonography and assessment with the Positive and Negative Syndrome Scale (PANSS) were performed on 28 acutely psychotic, neuroleptically naive, first-episode schizophrenics. In the second examination, the same patients were assessed psychometrically (PANSS) as well as with Doppler ultrasonography after psychopathological improvement. RESULTS Acutely psychotic first-episode schizophrenics showed a significant increase of the mean velocity on both sides in the middle and anterior cerebral arteries and in the right posterior cerebral artery. Blood flow showed significant correlations with productive psychotic symptoms. After psychopathological improvement there was a bilateral normalization of the mean velocity in the middle, anterior, and posterior cerebral arteries. CONCLUSIONS Acutely psychotic first-episode schizophrenics show a significantly increased bilateral cerebral blood flow velocity, which normalizes on psychopathological improvement. There were significant correlations of cerebral blood flow velocity with psychopathology.