The aim of this pilot study was to determine the sensitivity of HMPAO-Single Photon Emission Computed Tomography (SPECT), a new technique for determining cerebral blood flow. 7 RDC-schizophrenics, 5 schizoaffectives and 6 depressives were investigated after remission of the psychosis. It appeared that in the schizophrenics the blood flow was significantly reduced in the left anterior region in the infraventricular and ventricular section when compared with the depressives. This finding is discussed here. Apparently, HMPAO-SPECT is another valuable technique for investigating cerebral blood flow.