Because of the extremely limited potential of damaged articular cartilage for either repair or regeneration, and the fact that prosthetic joint replacement is contraindicated for children and young adults due to wear, loosening and mechanical failure of the artificial joint, there is a need for biologieal resurfacing of large, full-thickness defects in diseased or damaged joints by transplantation of a tissue with significant chondrogenic potential. The purpose of this study was to investigate the chondrogenic potential of free intra-articular autografts of the perichondrium or periosteum under the influence of joint motion, to characterize the newly formed cartilage, and to determine which is the more effective method to repair the articular defect. In a rabbit model, rib perichondrium and rib periosteum were used to repair full-thickness defects in the femoral condyle. The newly formed tissue was then evaluated grossly, histologically and histochemically at four, eight and twelve weeks after grafting. Successful grafts of the perichondrium or periosteum proliferate to fill the full-thickness articular cartilage defect with neocartilage which produces glycosaminoglycans in the matrix, as demonstrated by the uptake of saframin O. This production of a large amount of glycosaminoglycans in the reparative tissue is similar to that of hyaline cartilage. Unacceptable results were obtained in 38% of the perichondrial grafts, and in 32% of the periosteal grafts. These failures were due to femoral condyle fractures, and detachment of the grafts or failure of proliferation of the grafts. There was no statistically significant difference between the final results of the perichondrial and periosteal grous(p>0.1). The technique of grafting must be improved to increase the rate of successful grafts in which neocartilage resembling hyaline cartilage fills the articular cartilage defect. The positive results of the present experimental investigation prove that biological resurfacing of full-thickness defects in osteoarthritis, especially of small joints, may be clinically possible through the use of free autogenous perichondrial or periosteal grafts. Such biological resurfacing would be a valuable alternative to prosthetic joint replacement, especially in the treatment of children and young adults.