Four total knee arthroplasties were performed in 3 patients with the diagnosis of classical Charcot's joints associated with syphilis during past 4 years from 1985 to 1988. All patients had positive reaction in serology test(VDRL, TPHA). We corrected the bone loss and severe joint instability with allograft or autogenous bone grafting and ligament balancing. The knee score was increased from preoperative 37 points to postoperative 87.3 points. We expect that total knee arthroplasty may be the alternative treatment to the conservative treatment or knee arthrodesis in Charcots joints.