Layer-by-layer arrangement of the commissural and associative fibers has been studied in the cat parietal cortex. The commissural fibers are distributed in all the layers of the parietal cortex in the contralateral hemisphere, except the superficial part of the I layer. These fibers mainly terminate in the III, IV layers of the contralateral parietal cortex, though their termination in other layers is not excluded. The associative fibers of the parietal cortex are distributed in all the layers of the sensomotor area, except the superficial part of the I layer. They mainly terminate in the III, IV, V layers of the primary somatosensory and in the III, V layers of the motor cortex.