The effects of addition of Schwann cells on peripheral nerve regeneration through a novel graft material-the tendon autograft-and a conventional freeze-thawed muscle graft, were studied in the rat sciatic nerve. Adult Schwann cell cultures were established from predegenerated nerves. The Schwann cells were added to the autologous grafts by coculture (tendon autograft) or injection (freeze-thawed muscle graft). Both graft types supported adherence of the added Schwann cells. Addition of cultured Schwann cells to the two different graft models improved regeneration by increasing the rate of axonal outgrowth as compared with similar grafts without added cells