The aim of the study was to examine the action of low-dose amisulpride (100 mg/d), an atypical antipsychotic from the benzamide class with a high affinity for the D2 and D3 dopamine receptors, given for 4 weeks in 19 schizophrenic patients with the deficit syndrome, in terms of clinical response, modifications in their cognitive performance and changes in brain perfusion values. A secondary objective was to distinguish between primary and secondary deficit, according to Carpenter's definition. Both efficacy and a relatively low rate of side effects of low-dose amisulpride in the deficit forms of schizophrenia were found as expected from earlier placebo-controlled studies. Our study found significant changes in the cerebral blood flow, before and after treatment, more marked in the frontal area and particularly in the dorso-lateral frontal area. A significant improvement of cognitive function was found after treatment, without a link to any particular changes in a loco-regional perfusion value. Finally, a distinction between primary and secondary deficit showed a higher percentage of clinical improvement in the patients with a secondary deficit. The psychometric and cerebral perfusion changes were no different in the two groups.