From January, 1994 through March, 1995, 20 cases of CSF rhinorrhea happened during operation. The ages ranged from 20 to 76 years old. The types of tumors were: communicating craniofacial malignant tumors in 3 and pituitary adenoma in 17.The CSF fistulas were all repaired with autogeneous free muscle flaps, fat grains and gel foam, "threeinone" method. The defects of sphenoid and ethmoid bones and the dura mater ranged from 1.5 to 3.5cm and the filling materials used were 2 to 3 grams of fat grains and a muscle flap of 24cm in length, 1.82.5cm in width and 0.50.8cm in thickness. The survival rate from the implantation was 100 per cent, with satisfactory results. The patients were followed up for 1 to 14 months without any ill effect and recurrence of CSF rhinorrhea. The selection of the implanted material and its preparation were discussed. The main points in the surgical technique were introduced, and the mechanism of the implanted tissue was discussed preliminarily.