The main functions of articular cartilages are load-bearing and reducing friction of the articular surfaces. Because the capacity of articular cartilage to repair is limited, many attempts have been made to repair articular cartilage defects, which include transplantations of various tissues or cells. Within them, autologous cultured chondrocyte or autologous bone marrow mesenchymal cell transplantations are reported to be useful methods to repair articular cartilage defects. Here, we introduce these methods of tissue engineering and gene therapy, which are expected to become new treatments of articular cartilage defects.