Background: Supracondylar humerus fractures (SHF) are the second most common fracture in children and the most common fracture in children under seven years. Subtle neurovascular lesions in displaced SHF may be underdiagnosed clinically, but their sequelae can mean life-long symptoms. Here we show that color-coded duplex ultrasound (DUS) could help to identify these patients.Methods: We reviewed records of 229 children who had recovered from SHF. Ninety patients were available for detailed questionnaires, in-depth neurovascular examinations, and DUS.Results: In 90 examined patients, only two had been known to have suffered from vascular complications before our study. Only one still complained spontaneously about perfusion-induced symptoms. Qualitative changes in blood flow in duplex-sonography were detectable in both. Another two patients showed similar changes in blood flow at the fracture site. Both reported load-induced pain and paresthesia on detailed inquisition when no vascular impairments had been known before. Thus, duplex-sonography identified two patients with vascular affections that had not been noticed before in routine clinical examinations.Conclusion: DUS can be a sensitive tool in diagnosing vascular impairments in patients with SHF. It could reduce diagnostic insecurity, especially in anesthetized or otherwise hard to examine children, and thus help avoid the therapeutic delay that otherwise might foster life-long sequelae for the patients. More studies are needed to establish age-adjusted reference values for duplexsonography of children's arms. Level of Evidence: Level III, Study of nonconsecutive patients (without consistently applied reference).Abbreviations: AO = Arbeitsgemeinschaft Osteosynthese, DUS = color-coded duplex ultrasound, ED = end-diastolic flow, SHF = supracondylar humerus fractures, SS = systolic peak flow.