Six patients underwent arthroplasty of the trapeziometacarpal joint of the thumb with our ball-and socket type ceramic prosthesis for the osteoarthritis of Eaton stage 3 or 4. Our prosthesis was made of alumina ceramic and high-density polyethylene. Pain and dislocation or subluxation of the trapeziometacarpal joint were found in all of the patients preoperatively and these symptoms were relieved completely after surgery. The % total active motion of the trapeziometacarpal joint and metacarpophalangeal + interphalangeal joints, the % grip strength and % pinch strength improved postoperatively. The trapeziometacarpal joint function according to Eaton’s criteria after surgery was excellent of 5 patients and good of 1 patient.