This retrospective study compares the long-term results of the treatment of 135 children with displaced extension-type supracondylar fractures of the humerus using 3 different methods. Closed reduction and percutaneous fixation was superior with excellent and good results in 87% and had the lowest incidence of poor results (8%). Open reduction and wire fixation, and closed reduction with a plaster cast gave excellent and good results in 74% and 60% respectively. Closed reduction and wire fixation is recommended as the treatment for grades II and III supracondylar fractures.