Objective: Ultrasonography (US) is not the method of choice for the diagnosis of calcaneal fractures. The aim of this study was to compare the diagnostic accuracy of US with plain radiography in the diagnosis of calcaneus fractures following blunt ankle and foot trauma. Methods: In this cross-sectional study, 214 patients (over 18 years) presenting to the emergency department (ED) with suspicion of traumatic calcaneus fracture following acute blunt trauma, were enrolled. Bedside ultrasonography was performed and interpreted by emergency physicians. After that, plain radiography was performed. Furthermore, all the patients were assessed by computed tomography (CT) scan as the gold standard. Results: Finally, 193 patients were enrolled with a mean age of 29.4 ± 15.7 years (85.5% male). Fractures in the calcaneus were detected in 49 patients. The sensitivity and specificity of ultrasonography in the detection of calcaneal fractures were 83.6%, (confidence interval (CI), 69.7-92.2) and 100% (95% CI, 96.7-100), while the sensitivity and specificity of X-ray were 87.7% (95% CI, 74.5-94.9) and 100% (95% CI, 96.7-100). There was no false positive result for X-ray and US. Conclusion: Our findings suggest that bedside US with an acceptable sensitivity and specificity can be used as a promising alternative for the diagnosis of calcaneal fracture in ED.