There is no consensus on the best way to treat complicated fractures of the proximal humerus. Open reduction and internal fixation with plate is one of the most popular method, but it has several disadvantages. Thus we used bent semitubular plates to fix the proximal humeral fractures, which were reported by Szabo and Sehr. Moda etc. This method provided relatively firm fixation and then early ROM exercise was possible even in case of osteoporotic or severely comminuted fractures. We treated 9 cases of proximal humerus fractures which were with bent semitubular plates from January 1992 to June 1996 and followed up more than 6 months. The following results were obtained. 1. The bent semitubular piate fixation was useful method even in treatment of comminuted or osteoporotic proximal humerus fractures. 2. The mean duration of radiologic bone union was postoperative 10 weeks. 3, Complications developed in 2 cases ; one case was plate failure and the other was humeral head penetration by blade portion. 4, According to Neer criteria 5 cases were excellent, 2 cases satisfactory, 1 case unsatisfactory and 1 case failure.