We compared the clinical and radiographic outcomes between plate fixation and antegrade interlocking intramedullary fixation for humeral shaft fractures requiring operative intervention. Through retrospective, radomized comparative study, a total sixty adult patients have been reviewed. Thirty patients were treated with plate fixation, thirty another patients were treated with antegrade interlocking intramedullary fixation. Average follow-up time was two year and five months(range, one to four years). Average time to union was 10.8 weeks in plate fixation group and 16.9 weeks in intramedullary fixation group. Overall rate of union was 100% in plate fixation group and 90 % in intramedullary fixation group. According to Stewart and Hundleys functional assessment system, excellent or good results were obtained 29 cases(97%) in plate fixation group, 24 cases(80%) in interlocking intramedullary fixation group. In the plate group, only one fracture had deep infection but in the nail group, nine fractures had complications : three with nonunion, three with shoulder pain and limited ROM, two with intraoperative comminution and one with postoperative radial nerve palsy. There were some technical problems in antegrade intramedullay nailing such as difficulty proximal locking, failed expanlion of distal locking, iatrogenic fracture and distraction between fracture fragment. We concluded that the results after plate fixation have been shown to be preferable with respect to clinical and functional outcomes. In our study, the majority of circumstance requiring internal fixation, plate fixation is proferred and antegrade intramedullary fixation must be used in inevitable situation such as multiple trauma patients, fracture with overlying burns, patients with osteoporotic bone, pathologic fractures and segmental tractures.