The degenerative arthritis following total menisectomy has led to consideration of the need for meniscal transplantation, this study evaluates the morphologic and histologic changes fol lowing fresh meniscal autograft and allograft in therabbits. Transplantation of the medial meniscus was carried out in two groups of 32 rabbits(autograft group=16 rabbits, allograft group=16 rabbits). The morphological and histological changes of the transplanted auto-and allografted menisci and the articular cartilage of the medial femoral and tibial condyle were observed at 2,4,6,8,10,12,22,28 weeks postoperatively. There were no significant differences between auto and allograft groups in gross appearance. Histologically, the fibrous adhesion was noted between grafted meniscus and joint capsule 2 weeks after operation, but complete healing was seen at the suture sites without rejection phenomenon at 6 weeks in both groups. There were prominent inflammatory reactions such as lymphocytes and inflammatory cells infiltration during early postoperative stages(2,4 weeks) only in the allograft group, and more prominent fibrotic reactions in the allograft group than auto-graft group. The results of this study suggest that meniscal allografts are able to adapt to the host tissues, survive within the joint environment, and provide a functional replacement for the removed meniscus, but further studies for graft-host immune response and a method to take the maintenance and deposits of graft must be needed to perform the meniscal allograft in human.