Many methods have been proposed for treatment of displaced humeral shaft fractures in adults. This study was designed to evaluate the anatomical and functional results of patients treated by retrograde intramedullary nailing through the lateral condyle. Sixty-three fresh traumatic fractures of the humerus were treated between January 2000 and January 2003. Five patients were lost to follow-up. The AO classification and the Hackethal classification modified by De La Caffinière were used. Outcome was assessed according to the modified Stewart and Hundey classification. We had 23 very good results, 26 good results, five passable results and four bad results. The bad results were three cases of non-union and one case with poor function (stiffness of elbow and shoulder). Mean delay to union was ten weeks four days. There were no cases of iatrogenic radial nerve palsy or pin migration. Retrograde intramedullary nailing is a reliable method, easy to perform and of low economic cost. We propose it for all types of displaced shaft humeral fractures.