We examined whether giving monoclonal antibodies (MoAb) to intercellular adhesion molecule 1 (ICAM-1) and leucocyte function associated antigen (LFA-1), which have important roles in the initial stage of rejection after allografts, can improve nerve regeneration in allogeneic mice. Fresh sciatic nerves were grafted using BALB/c mice as donors and C3H/He mice as recipients. Nerve regeneration at six weeks was significantly better in the mice given MoAbs at one and five days than in those given none (n = 5 in each group), although nerve regeneration even in the five-day group was significantly inferior to that in the syngeneic nerve graft group (n = 5). The survival time of the nerve donor skin graft at 12 weeks was not prolonged by treatment with MoAbs, indicating a failure to induce immunological tolerance. However, at 10 months after nerve grafting there were fewer Mac-1, Lyt-1, and Thy-1 positive cells in the five-day group and they showed less immunoreactivity than the untreated group. We conclude that giving MoAbs could effectively improve nerve regeneration in grafted allogeneic nerve segments, although it did not induce immunological tolerance.