Background: Ultrasonography is an important diagnostic tool for many aspects of clinical medicine. It is a non-invasive method of examination that provides high-resolution images in real time. However, some dermatologists may be anxious about the efficacy of ultrasonography. Objective: To evaluate the diagnostic accuracy and to assess the utility of diagnostic ultrasonography for subcutaneous benign lesions. Methods: The study included 96 patients with subcutaneous benign lesions who underwent ultrasonography and then received a pathologic diagnosis after biopsy or surgery at our hospital from July 2010 to December 2012. This study evaluated the number of cases in which the preoperative diagnosis after ultrasonography or just after physical examination agreed to the pathologic diagnosis. Results: Ultrasonography significantly increased the diagnostic yield of subcutaneous benign lesions (after physical examination, 54.2%; after ultrasonography, 84.4%; p＜0.001). The sensitivity for the diagnosis of lipoma (after physical examination, 70%; after ultrasonography, 92.5%; p＜0.001) and the specificity for the diagnosis of epidermal cyst (after physical examination, 84.1%; after ultrasonography, 94.2%; p＜0.001) significantly increased after ultrasonography. The sensitivity for the diagnosis of epidermal cyst and pilomatricoma also tended to increase after ultrasonography. Conclusion: The study results suggested that ultrasonography is useful for diagnosis and/or preoperative examination of subcutaneous benign lesions.