The increase in severe ligament injuries of the knee has led to consideration of the need for meniscal transplantation in reconstructive operations for chronic rotational instability. Transplantation of the medial meniscus was carried out in two groups of 15 sheep. In one group lyophilised, gamma-sterilised allogenic menisci were transplanted and these underwent a complete remodelling in 48 weeks. In the other group, deep frozen allogenic menisci were used and these remained fully functional without remodelling. We then carried out meniscal transplantation in 22 patients who were followed-up for a mean of 14 months. Arthroscopy was possible in two-thirds of the cases at an average of 8 months after operation. Both types of transplanted menisci, lyophilised and deep frozen, decreased in size, as small as a regenerated meniscus in some cases. In general the deep frozen menisci showed better results.