The author treats the subject under the following heads:— I. A short historical and critical review of the books and papers which have appeared on the subject from the time of Cruik-shank (1776). II. Clinical reports of four cases of secondary suture of nerves as follows:— 1. Suture of the median and ulnar nerves six and a half months after division in the middle of the forearm. There was total loss of sensation and motion in the distribution in the hand, and marked atrophic changes. Three days after the operation, sensation commenced to return; by the nineteenth day, touch was correctly localised on all parts of the fingers; and by the end of the first month, sensation was almost perfect. Improvement in motion was slow and imperfect.