We report our experience with a modified implant and a new technique for locked intramedullary nailing of the humerus in 41 patients. Locking was by cross-screws placed from lateral to medial in the proximal humerus, and anteroposteriorly in the distal humerus. Early in the series, 11 nails were inserted at the shoulder, but we found that rehabilitation was faster after retrograde nailing through the olecranon fossa, which was used for the other 30. We used a closed technique for 29 of the nailings. Of the 41 patients treated, 21 had acute fractures, five had nonunion, and 15 had pathological fractures. Secure fixation was obtained for comminuted and osteoporotic fractures in any part of the humeral shaft, which allowed the early use of crutches and walking frames. Two nails were locked at only one end, and one of these became the only failure of union after an acute fracture.