The current retrospective study refers to 61 fractures and nonunions of the humeral shaft that were treated operatively between 1980 and 1990 in the Department of Surgery of the University of Zurich Medical School. All fractures were stabilized with thin noninterlocking AO tibial nails. The follow-up included 48/61 patients. The predominant fracture localization was the middle third of the humeral shaft (52 consecutive cases), and most of these fractures were of the simple transverse type A3 according to the AO classification (29 cases). The incidence of initial radial nerve palsy was 9/61 and that of postoperative palsy 1/61. No preoperative evaluation of radial nerve function was obtained in 4 multiply injured patients. Upon follow up, the function was found to have returned to normal in 8 patients. No infectious complications were observed. In 4/56 patients the final result was nonunion. In 41/48 a good result was obtained in terms of shoulder function. There were 7 patients (5 of them multiply injured) with poor shoulder motion with less than 100 degrees in abduction and anteversion.