Ten patients who had a clavicular nonunion were treated operatively at the Catholic University of Taegu Hyosung, with semitubular plate and small LC-DCP from 1987 to 1996. The most common mechanism of the initial fracture was direct injury in eight cases and the most prevalent location of the nonunion was in the middle third in eight cases also. The purpose of this study is to evaluate the functional and radiological results of the treatment of the clavicular nonunion with the technique of semitubular plate and small LC-DCP and to verify the anatomical configuration and mechanism of the clavicular fracture. The results were as follows: 1. According to the comprehensive classification system, initial fracture type consisted of 8 cases of III-B, and 1 case in II-B and I-B alternatively. 2. Initial treatment was conservative in 8 cases, operative in 2 cases and the treatment of the nonunion was an operative technique with semitubular plate and LC-DCP in 5 cases alternatively. 3. Iliac bone graft was done in all cases and radiological union was achieved by 7.5 weeks with STP group, by 8 weeks with LC-DCP group. 4. The functional result by Weitzman classification was excellent in 4 cases, fair in 1 case with STP group and excellent in 3 cases, good in 1, and fair in 1 case with LC-DCP group. 5. LC-DCP was considered as a recommendable device because it could afford sufficient strength and reduce local osteoporosis of the bone.