Operative treatment of two-part, displaced surgical neck fractures of the proximal humerus is used when satisfactory closed reduction cannot be achieved or maintained. Recently, we modified the Ender nails by making an additional hole above the slot for wire incorporation. The purpose of this study was to assess the effects of stabilization of displaced and unstable surgical neck fractures of the humerus by Ender nailing and tension band technique. We reviewed the data of fourteen consecutive patients (10 women and 4 men) who had been treated with Ender nailing and tension band wiring between from Aug 1996 and Oct 1997 at Eulji Medical College Hospital. The average age of patients was 54 years (range, 38 to 79 years), and the average follow-up period was 18 months (range, 12 to 24 months). Bone union was observed at 6.3 weeks (range, 5.5 to 10 weeks), except one case of delayed union. There were no infections and nonunions. The average ranges of shoulder elevation and abduction were 140 degrees(100 degrees to 170 degrees) and 126 degrees(100 degrees to 160 degrees), respectively. The median value of the thumb to vertebral distance was L1, with a range of T6 to L5 for internal rotation, external rotation was 48 degrees (30 degrees to 70 degrees) . Radiography revealed one case of medial shift greater than 5mm, and 4 cases of lateral shift greater than 5mm of the humeral shaft. The average varus angulation of the humeral neck was 8.5o(0 degree to 34 degrees). Four patients (28.6%) were excellent (34 to 35), six patients (42.8%) were good (28 to 33), four patients (28.6%) were fair (21 to 27) in UCLA shoulder rating scale. In conclusion, Ender nailing and incorporation of the tension band wire loops provided additionally rotational and longitudinal stability in two-part displaced surgical neck fracture of the proximal humerus associated with osteoporosis.