We tested the potential of a new technology developed in our laboratory to create new hyaline cartilage for resurfacing distal femoral joint surfaces of New Zealand White rabbits that had been surgically denuded of articular cartilage. We removed hyaline cartilage from the patellar groove of the distal femurs in 24 rabbits. Chondrocytes isolated from the excised cartilage of 12 of these rabbits (experimentals) were seeded onto synthetic biocompatible, biodegradable polymers composed of polyglycolic acid. The cells were labeled in vitro with a thymidine analog, BrdU (5-bromo-2'-deoxyuridine). After 1 week in vitro, the cell-polymer structures were implanted onto the denuded surfaces of 12 defects made in the hyaline cartilage of the contralateral knees of the experimental animals. Twelve control animals received either no implants or implants not containing cells on similar surgical defects. After 7 weeks, we found evidence of new cartilage growth in 11 of the 12 experimental animals and virtually no new cartilage formation in any of the animals in either control group. Immunohistochemical analysis demonstrated the presence of BrdU-labeled chondrocytes in representative specimens.