It is possible to seal nerve ends together with the laser, and this can be effective for sharp injuries that are repaired relatively acutely or primarily. The possibility of utilizing the laser for secondary nerve repair after resection of a lesion in continuity was investigated in a rat sciatic nerve model. After baseline recording of nerve and muscle action potentials (MAP), a 3-mm-long crush injury of the sciatic nerve was performed bilaterally in 12 rats. Two weeks later, the crushed segment was resected, and the nerve on one side was repaired by end-to-end anastomosis using epineurial sutures and on the other side by sealing the nerve ends together with the CO2 laser. At reexploration 50 days postoperatively, all 12 suture repairs were anatomically in continuity and conducted a nerve action potential (NAP), while 10 of the 12 laser-repaired nerves had distracted. Laser repairs not distracted showed electrical and histologic evidence of regeneration. It is concluded that laser repair is not effective for delayed repair of lesions in continuity unless tension at the repair site can be lessened.