272 cases with visual field defects were examined by CT and analysed. 78 patients showed a chiasmatic lesion, 45 patients a lesion of the optic tract or the lateral geniculate body and 136 patients a lesion of the optic radiation or the occipital cortex. 96% of the CT pictures were topographically corresponding to the known optic field defect. In more then 75% of the operated patients the nature of the CT lesion was confirmed. 10 cases were negative in CT and 3 false positive. Because of the high rate of exact topographic diagnosis CT should be the initial investigation in visual field defects. But the nature of a lesion has to be diagnosed with caution, taking into account the entire clinical picture.