Investigations conducted in 20 joints of 17 dogs suggest that a Teflon-net substitute meniscus preserves knee joint functions more effectively than a regenerated or absent meniscus. Teflon-net is an ideal material for meniscal replacement because it is easily obtainable, has flexibility and histo-compatibility, and is rapidly infiltrated with cells. A comparative study should be undertaken of knee joint functions with the substitute meniscus and the remains of the meniscus after partial meniscectomy before clinical use of the Teflon-net is feasible. The adhesion between the substitute meniscus and the popliteal muscle also requires further laboratory investigation.