From retrospective review of 26 humerus fractures treated by Seidel interlocking intramedullary nailing, 17 complications in nine patients(35%) were occurred: two delayed unions, three malunions, two infections, one distraction of fracture gap, two additional fragmentations, two failures in proximal interlocking screw insertion, three distal locking mechanism failures and two proximal protrusions of nail. Functional assessment was carried out an all patients at a mean follow up 13 months(9-23 months). The results were ten excellent, twelve good, two fair and two poor. These results show that there are considerable problems at present in the use of the seidel interlocking nail.