Transplantation of allogenic devitalized matrices carrying autologous chondrocytes previously isolated and seeded on them might solve the problem of repairing joint cartilage lesions. This study analyzes the mitotic activity of chondrocytes seeded in allogenic devitalized cartilage and implanted in living animals. Chondrocytes of joint cartilage of lambs were enzimatically isolated and seeded in vivo in allogenic devitalized matrix during three weeks. At the end of the co-culture period, the matrix compounds and chondrocytes were transplanted into subcutaneous pouches of atymic mice. Histological evaluation of the experimental and control samples was performed following incorporation of tritiated thymidine. The results showed a significant reduction in thymidine incorporation values, as of experimental moment zero (pre-implant evaluation) up to implant day 28, following by a slight increase by day 42 of the study. This experience has shown that joint chondrocytes (seeded in vitro and then transplanted in vivo on an allogenic devitalized matrix), tend to change their own mitotic activity from very high levels, corresponding to the initial experimental days (typical of the in vitro phase of cell proliferation), to very low levels, resembling the performance of in vivo joint chondrocytes.