Tinel's sign, formication or distal tingling on percussion (D. P. T.), is, as described by Tinel, a creeping sensation in the cutaneous distribution of an injured nerve when compression or percussion is lightly applied along its course peripheral to the injury. The sign indicates that the axis cylinders are in process of regeneration. The following conclusions relative to the importance of this sign were reached after 2,500 personal examinations in over 500 cases of peripheral nerve injury, operative and nonoperative. The patients had been injured at least three months prior to their entrance to General Hospital No. 6. Examinations were made monthly as a matter of routine. TECHNIC With all muscles of the part relaxed, gentle finger percussion is performed, beginning as near the distal distribution as possible and proceeding proximally. INDICATIONS 1. Progressive formication is not an infallible sign of regeneration in a peripheral nerve. It may be present