Single neuronal recordings in the first somatosensory cortex of the monkey have shown the presence of systematic hierarchical processing along the rostrocaudal axis of the postcentral gyrus. Neuronal activity to code types of hand manipulation or features of tactile objects were found in the caudal part of the gyrus, indicating that the postcentral hand region is organized to process tactile and kinesthetic information for active touch. The hierarchical scheme led us to find neurons representing bilateral sides of the body in the postcentral-intraparietal region. Certain bilateral neurons could contribute to inter-manual transfer of tactile information. Other bilateral neurons appeared to represent bilateral body surfaces or limb positions. Still other bilateral neurons could represent the peripersonal space since they responded to the visual stimuli presented in the space over the somatosensory receptive field. We further studied neuronal receptive field properties in the parietal opercular region and confirmed that in the second somatosensory cortex (SII) neurons with larger and converging receptive fields covering remote and discontinuous body parts were common and consequently SII was organized much less somatotopically. Functional roles of the postcentral, intraparietal and SII regions in the somatosensory processing were discussed in the light of these single neuronal receptive field studies and recent brain imaging studies in humans.