Abstract A copolymer (polylactic acid: polyglycolic acid) was combined with a proteolipid (PL) and the resulting implant complex was rigidly fixed into discontinuities in the mandibles of 25 adult, foxhound dogs. Identically prepared control discontinuities in contralateral sites in the same animals were also rigidly fixed but did not receive the complex. At four, eight, 12, 24, and 40 weeks the dogs were killed and implant and controls were prepared for histomorphometry. Histomorphometric evaluation revealed a linear increase of bony reparative elements in the implants over 40 weeks that exceeded those of the nontreated control sites. The copolymer-PL implant, therefore, may provide an alternative to autogeneic and allogeneic bone substances.