Plastic is used in addition to metallic osteosynthesis in fracture treatment. The object of the present study was to test the usefulness of plastic as the sole fixation material in experimental osteotomies of cancellous bone and in tibial cortical bone grafts. A total of 32 rats were used. In the first group, consisting of 12 rats, the lateral condyle of the right femur was detached and refixed with Silar. In the second group, a tibial cortical bone graft was detached and refixed with Silar in 12 rats and left unfixed in eight. In the first group fixation of the condyle was successful in all cases but one, but in the second group sufficiently stable fixation of the cortical bone graft was not attained and fractures occurred in half the cases.