A deep shaving of partial resection of the articular cartilague of the patella was performed in a first series of 14 rabbits following a 12 weeks rebuilding evolution. A degeneration of the remaining articular cartilague appeared after the seventh week giving way to severe ostheoarthritis of the patella. 1 n a second series of 18 rabbits a «spongialization» of the articular surface of the patella was performed, an histological study was followed along 36 weeks. The articular surfa-· ce was invaded by fibrocartilagous tissue from prolification and metaplasia of the subchondral marrow. This new tissue became progressively deteriorated from the fifth week. After nine weeks the degeneration became in severe ostheoarthritis changes. This experimental work leads to discuss the worth-while biological value of the surgical technique of deep-shaving and the spongialization for the surgical treatment of the chondromalacia and ostheoarthrosis of the patella, world-wide used.