Background Maxillofacial fractures are a common cause of visits to emergency department, accounting for more than 400,000 annual visits in the United States. Gold standard diagnostic tool is conventional computerized tomography (CT) or 3DCT reconstruction. However, the disadvantages of CT are radiation exposure, unavailable in some hospital and expensiveness. Whereas the bony structures overlap is a problem in diagnostic when using plain film X-ray. The objective of this study is to show the accuracy of a linear-probe ultrasound compared to computed tomography and plain film X-ray in diagnosis of infraorbital rim fracture. Methods Patients clinically suspected of an inferior orbital rim fracture underwent linear-probe ultrasonographic investigation, plain film X-ray and CT. CT was used as gold standard in this diagnostic study. A radiologist and senior resident of plastic surgery were the examiner and interobserver for comparison. Result A total of 34 patients with suspected infraorbital rim fractures were investigated. Sensitivity of the linear-probe ultrasonography versus CT in the detection of infraorbital rim fracture was 92.9% (95% CI 66.1–99.8), specificity was 90.0% (95% CI 68.3–98.8), positive predictive value was 86.7% (95% CI 59.5–98.3), negative predictive value was 94.7% ( 95% CI 74.0–99.9), accuracy 91%. Conclusion Linear probe ultrasonography is a good diagnostic tool and has better reliability than the plain film X-ray and can be used as alternative to CT in inferior orbital rim fracture.