Various techniques for treatment of large bone defects have been reported, instead of using autogenous bone graft. The author have applied and explored for bone repair with polyglactin 910 mesh and fresh fascia late. Full thickness 8x8mm bone defects were made on the frontoparietal bone of rabbits and group 1 defect was covered with polyglactin 910 and group 2 defects with fresh fascia late, but group 3 and 4 were not covered. However the periosteum was left on group 4 but it was not left on group 3. Samples were taken from the operation site for clinical and histological examinations on 2, 4, 8 and 12 weeks after operation, repetitively. The results were as follows ; 1. On the group 1, where ployglactin 910 mesh had been placed, the defects taken in 2, 4 ,8, 12 weeks after operation disclosed osseous regeneration with newly formed bone but the thickness was much less than the original bone. 2. On the group 2, where fresh fascia rata had been placed, the defects taken in 2, 4, 8, 12 weeks after operation disclosed same pattern of group 1. 3. On the group 3 and 4, where membrane had not been placed, the majority of the defects consisted of connective tissue and muscles. 4. On the group 1, resorption of polyglactin 910 mesh was completed after 4 weeks, but on the group 2, the fascial rata still remained intact.