The authors tested the hypothesis that photic visual stimuli cause a greater blood flow activation response in subjects with schizophrenia than in normal subjects. Eleven medicated patients with schizophrenia and 10 normal subjects were studied with [15O] H2O positron emission tomography to measure perfusion during photic stimulation at four different rates. The activation at three out of four rates of visual stimulation was greater for the patients with schizophrenia than it was for the normal subjects. Further investigation into the mechanisms of activation during sensory stimulation in schizophrenia is warranted.