Treatment of the injured peripheral nerve with a long defect remains one of the most difficult problems in nerve reconstructive surgery. Adipose derived mesenchymal stem cells(MSCs) have the potential to differentiate into neuronal and adipose tissue and osteogenic cells. We investigated the effect of MSCs on histological and functional regeneration of facial nerve. After transection of facial nerve in twenty rats, we divided the experimental animals into four groups. In five rats, direct anastomosis was done. In fifteen rats, nerve defect were connected with silicone tubes which were left empty or filled with fibrin or filled with fibrin and MSCs. MSCs were tagged with ferumoxides before transplantation. After 8 weeks, motion of the vibrissae was analyzed and histological examinations were performed. Amplitude and frequency of vibrissae were significantly larger in MSCs group. On H&E and anti-S100 immunohistochemical staining, the maximal diameter of the regenerated nerves was significantly larger in MSCs group. On Prussian blue staining, we could identify the MSCs in the regenerated nerve. We concluded that transplantation of MSCs into a facial nerve gap substantially increased axonal regeneration.