Transforming growth factor-beta1 (TGFbeta1) is a well- known, potent growth factor implicated in both in vitro and in vivo chondrogenesis. Liposomes have been employed as a drug delivery system to promote the efficient use of drugs. The objective of this study was to demonstrate that a single injection of liposomal TGFbeta1 has an accelerating effect on the repair of an articular cartilage defect. Full-thickness articular cartilage defects were prepared on the patellar grooves of the femurs in knee joints of Japanese white rabbits. One week after surgery, various reagents including liposomal TGFbeta1, free TGFbeta1, and phosphate-buffered saline were injected into the operated knee joints. At 3 weeks after surgery the specimens obtained from the lesions were evaluated histologically, and the glycosaminoglycan content was quantified. Histological examination revealed that the defects were filled with thicker fibrous cartilage and showed more intense metachromatic staining in the liposomal TGFbeta1 group than in the other groups. The glycosaminoglycan content of the repair tissue was also significantly higher in the liposomal TGFbeta1 group than in the other groups. This study indicated that the intraarticular injection of liposomal TGFbeta1 could accelerate the early-stage repair of full-thickness articular cartilage defects.