The purpose of this study was to present a new internal fixation technique for transcondylar fractures of the humerus in elderly patients. Seventeen patients, aged older than 70 years, with displaced transcondylar fractures were treated by our new surgical method. All fractures were fixed by a customized AO small T plate and a transcondylar screw passed from the lateral epicondyle to the medial wall of the trochlea across the humeral condyle. The plate was hand-shaped, trimmed, and applied at the lateral side of the fracture site, and either a cannulated cancellous screw or an AO one-third tubular plate was applied at the medial side of the fracture site. All patients in this study had osteoporotic bone and a small distal fragment. They were followed up for a mean of 30 months (range, 24 to 60 months). Radiographically, union was achieved completely in all patients, and all except 1 had maintained the postoperative alignment. Bone graft or cement fixation was not required in any case. The assessment of the results by use of the modified Cassebaum's rating scale was excellent in 3 cases, good in 11, and fair in 3. With the custom AO small T plate and transcondylar screw fixation technique, the screw that passes through the humeral condyle provides good stability even in cases with a small osteoporotic fragment of the distal humerus. The screw does not damage the articular surface of the elbow joint, and stable fixation can be obtained even in osteoporotic bone.