BACKGROUND Supracondylar humeral fractures are the most common elbow fractures in children. In case of displacement and instability, the standard procedure is closed reduction and percutaneous Kirschner wire fixation. As Kirschner wire fixation requires postoperative cast immobilization, does not allow early mobilization, and is associated with the risk of damage of the ulnar nerve, innovative techniques should be evaluated. Therefore, the aim of the study was to assess both radiologic and functional outcome of supracondylar humeral fractures treated by elastic stable intramedullary nailing (ESIN) in a large pediatric cohort. METHODS Retrospective review of children who underwent closed reduction and ESIN of displaced supracondylar humeral fractures in our institution between 2001 and 2009. RESULTS One hundred twenty-seven children (mean age 6.1 y) with types II (60.6%), III (23.6%), and IV (15.7%) fractures according to the Arbeitsgemeinschaft für Osteosynthesefragen (AO) Pediatric Comprehensive Classification were included. One hundred and eighteen patients (92.9%) had healing of fracture without any limitation in range of motion and 9 patients (7.1%) had some minor degree of long-term functional deficit (7 children with flexion and 2 with extension deficit). Two children had clinical cubitus varus deformity. No iatrogenic damage to the ulnar nerve occurred and no secondary reduction or a change of surgical strategy was necessary. Postoperative radiologic evaluation showed antecurvation in 1 case, recurvation in 3 cases, as well as cubitus varus deformity and rotation deformity in 1 child each. CONCLUSIONS Antegrade ESIN is a technique suitable for all types of supracondylar humeral fractures with good functional results. The advantages include the avoidance of iatrogenic ulnar nerve injury, low rates of cubitus varus, cast-free treatment, and the possibility to evaluate clinical motion at all times postoperatively. Although biased toward milder forms of supracondylar fractures, our data clearly suggest that if closed reduction is possible, intramedullary nailing in these children is more than an alternative to Kirschner wire fixation as the standard procedure. METHODS IV.