Purpose: To evaluate the results and complications of antegrade intramedullary interlocking nailing in humerus shaft fractures. Materials and Methods: We evaluated the clinical outcomes, radiologic results and complications in 47 patients with humerus shaft fracture treated with antegrade intramedullary interlocking nailing, and followed up until bony union. Bony union was confirmed by serial plain radiographs and the clinical outcomes were assessed according to the ASES scoring system. Results: Bony union was confirmed in 41 (87.2%) out of a total 47 patients, and the mean union period was 14.5 weeks. Major complications were as follows: 6 non-union, 3 delayed union, 2 intraoperative posterior cortex fracture in the distal humerus and 2 permanent shoulder pain, including 1 case of adhesive capsulitis. The clinical outcomes were as follows: 29 excellent, 11 good, 4 fair and 3 poor. Satisfactory outcomes were demonstrated in 40 patients (85.1%). Conclusion: Anterograde intramedullary interlocking nailing as treatment for humerus shaft fracture showed satisfactory bony union and clinical outcomes. It is considered an efficacious treatment, especially in patients with associated injury, such as multiple fractures and segmental fracture.