The aim of this work is to try to compare the results of different methods of circumferential small nerve suture according to the degree of magnification and type of microsurgical technique. Four techniques were studied in forty Wistar rats. 1. Microsurgical suture with the Set technique. Magnification 25, accurate suture. 2. Microsurgical suture with simple end to end approximation. Magnification 25, accurate suture. 3. Same technique, but delayed suture. 4. Suture with a simple end to end approximation. Magnification 4. Four stitches for reapproximation. After four months the sutured nerves have been studied both electrophysiologically and histologically. The results show clearly that the so-called set technique associated with an accurate circumferential suture with eight stitches under high magnification gives by far the best results, the regeneration rate of the nerve being higher than 80%. The results in groups 3 and 4 are definitely less good. The simple bringing together of both stumps under low magnification with only four stitches (group 4) gives the worst results with only 20% of regeneration.