Measurements of the cerebral cortical volume used to be very laborious, due to the 3-D complexity of the gyral pattern. Using stereological methods, which allow the quantification of 3-D structures from measurements on 2-D cross-sections, the difficulties have been overcome. In thirty formalin-fixed normal human brains the total volumes were measured by saline displacement. The brains were serially sliced in coronal sections and the fractional areas of the cortex, white matter, central grey structures and ventricles were determined by point-counting. Using Cavaliéri's principle the volumes of these structures were calculated. The average cortical fixed volume was 549 ml (SD +/- 107) corresponding to 54% of the total volume of the hemispheres. The coefficient of error of the cortical volume determinations was 2.6%. The efficiency of the design and the possibilities for optimizing the design are discussed. This point-counting method was preferred to the use of an automatic image analyser, being precise, easy to handle and not interfering with further tissue processing for histological preparation.