The distribution of pacinian corpuscles in the cat forefoot was investigated using celloidin sections stained with haematoxylin and eosin. The corpuscles were oval or elliptical, their longitudinal and transverse diameters being 590.0 +/- 207.6 microns and 320.0 +/- 119.6 microns. There were 667 corpuscles (mean value for 4 feet) in each forefoot, 80% of which were in the toe region and the remainder in the palmar region. The number of corpuscles was similar in both forefeet. There was no difference in light microscopic structure. Corpuscles were located (1) in the dermis and subcutaneous tissue of the skin folds covering the claw, (2) between the flexor digitorum tendon and middle phalanx, (3) in the subcutaneous adipose tissue of the metacarpal pad and (4) in short digital muscle of the carpal pad. Scattered corpuscles were found in contact with the periosteum of distal and middle phalanges and with flexor tendon sheath, and in the dermis of the palm. Corpuscles were observed to be clustered in the skin folds of the toes. Skin folds, made of dorsal hairy skin, covered the claw on both sides, with most corpuscles in contact with hair follicles and others scattered between hair follicles. Forefoot corpuscles were often in proximity with blood vessels. Corpuscles in the palmar region were seen to be arranged along the superficial palmar metacarpal nerve.