AIM Autologous grafting has developed into one of the preferred methods of treatment for focal osteochondral lesions, although basic research on this topic remains sparse. In an animal study, questions regarding the healing of such osteochondral transplants are clarified. METHOD An autologous osteochondral transplantation was performed on the ovine knee using the standard operative protocol. Two groups, consisting of 10 sheep each, were evaluated after 3 and 6 months, respectively. RESULTS During the clinical evaluation of the specimens, neither osteophytes nor synovial changes were observed. The consistency of the cartilaginous tissue began to reach a level equivalent to the surrounding tissue only after 6 months. Macroscopically, the superficial border of the transplanted osteochondral plug could easily be outlined at both time points. Radiographically, a solid osteointegration of the graft could already be documented at 3 months. In contrast, integration of the chondral surface of the OAT was not seen macro- or microscopically at any point in time. A firm physical interdigitation of the reconstructed joint surface could not be demonstrated. CONCLUSIONS The lack of integration of the cartilaginous portion of the transplanted plugs into the reconstructed joint surface leads to questions regarding the long-term survival of the joint itself.