Dynamic 133Xe Single Photon Emission Computed Tomography (SPECT) was used to measure the resting regional cerebral blood flow (rCBF) in 16 neuroleptic free schizophrenic and schizophreniform male patients and 13 age-matched male normal controls. A subgroup consisting of 'first break' patients who had never been exposed to neuroleptic treatment were age-matched to a subgroup of young chronic patients most of whom had been previously exposed to neuroleptics. The age-adjusted rCBF values were compared among first breaks, young chronics, normal controls, and a subgroup of older, more chronic patients. In first break patients, we found significantly lower absolute global cerebral blood flow and significantly lower superior frontal, middle frontal, and middle temporal absolute rCBF compared to normals. We also found significantly lower relative superior frontal rCBF in first breaks vs. normals, and higher relative superior frontal and relative middle frontal rCBF in older chronics vs. the other groups. For relative posterior temporal rCBF there was greater asymmetry (right side > left) in first breaks and young chronics compared to normals and older chronics.