Quantitative methods were used to examine the cerebral cortex of the albino rat. A computer-controlled automatic image analyzer was used to determine by a systematic scanning procedure the grey level index of the 60 X 60 mum measuring fields in Nissl-stained serial sections form three brains. Based upon various selected thresholds or ranges of grey level indices, topographically accurate computer plots were produced, and an areal pattern of the cortex worked out according to quantitative considerations. Maps of the cytoarchitectonic areas of the cortex were reconstructed graphically. The present analysis shows a cortical pattern which differs to a great extent from Krieg's (1946) classical description, but corresponds to the degeneration studies, studies on axonal transport and neurophysiological studies of various cortical areas as described in the literature.