THREE DIFFERENT METHODS of nerve repair were evaluated in an experimental model of spinal root injury. In adult rats, dorsal L4 roots were cleanly severed and repaired by microsurgical techniques. Anastomosis was performed by direct end-to-end suture, the arterial sleeve technique, or the interposition of a nerve graft. Results were evaluated 7, 10, and 14 weeks after surgery. Regeneration was studied by light and electron microscopy, showing a fair regenerative pattern in each group. The endoneurial connective response, including neovascularization, was more prominent after grafting. The artery sleeve technique is a very tedious procedure, and fibrosis around the artery and arachnoiditis were intense. A lack of continuity was found in 3 of 12 direct sutures. In conclusion, the best method for the reparation of nerve roots seems to be the interposition of a nerve graft.