Introduction: It is clear that the proliferation, migration and differentiation processes of embryonic fetal neural tissue are dependent on special trophic factors. These factors are absent or lessl seen in adult tissue. In this research the effects of Fetal Brain Extract (FBE) on the regenerational processes of lesioned prepheral nerve were investigated. Materials and Methods: The facial nerve of 16 Wistar rats on the anterior border of the garotid gland was unilaterally cut by a sharp blade. The rats were then divided in to experimental and control groups (n=8). The experimental rats were injected with 0.2 ml of fetal brain extract on 7, 14 and 21 day post operation, while the control rats received normal saline in the same manner. The rats were anesthetized and sacrificed on day 28 post operation and the lesioned region of the facial nerve was sampled (5 mm lenght). The samples were then fixed, processed, embedded in paraffin and cut serially in 7µ thickness and then stained with H & E and picofuchsin. Results: In comparison with the controlgroup a high number of capilary and high amount of connective tissues around the lesiond region existed in the experimental sampels. These results indicate that in the experimental group the trophic factors of fetal extract probably were, retrogradly transported to perikaryons and, in addition to the maintenance of cell body, help them to induce regeneration in the proximal end of nevre fibers. FBE has probably local effects on the connective tissue which are necessary for regeneration.