Systemic injection of MPTP damages the nigrostriatal dopaminergic system in C57B1/6 mice. Since transected peripheral nerve segments are known to produce nerve growth factor, we performed adrenal medullary grafts or cografts of adrenal medulla and sciatic nerve into the striatum of MPTP-treated mice, and compared the survivability of grafted chromaffin cells and the recovery of intrinsic host dopaminergic fibers. Survivability of grafted chromaffin cells increased when cografts with sciatic nerve were made, and host dopaminergic fiber recovery was more prominent in mice with cografts than in mice with adrenal grafts alone. The degree of recovery of host intrinsic dopaminergic fibers was greater in younger host striatum than in older host striatum. We conclude that cografts of adrenal medulla and sciatic nerve increase the survivability of grafted chromaffin cells better than adrenal medullary grafts alone, and that survivability of grafted chromaffin cells promotes host dopaminergic fiber recovery.