Ultrasonography is suited for screening patients with a mass in the soft tissue because of its safety, low cost, apparent sensitivity and non-invasiveness. But the application in orthopaedic surgery is insufficient. Authors examined 102 patients who had a palpable soft tissue mass of extremities and trunk with ultrasonography. Location, internal echogenicity, margin, and extent of soft tissue involvement, especially neurovascular bundle by tumor were evaluated. The diagnosis of mass was confirmed by histopathology after excision or biopsy of the mass. The ultrasonography correctly identified and differentiated the cystic lesions of 34 cases. The sonograms of all 16 malignant lesions showed ill-defined margin and heterogenous internal echo. The extent of soft tissue involvement, especially neurovascular bundle was confirmed exactly with ultrasonography. Therefore, in malignant tumor, after confirmation of no neurovascular involvemment with ultrasonography, limb-salvage operation could be considered and planned. In one case of abscess, percutaneous biopsy was done under guidance of ultrasonography. Therefore, ultrasonography can be used as a guide for percutaneous biopsy without exposure to radiation.