52 patients who had soft tissue lesions in extremity, buttock and shoulder, were studied by ultrasonography toevaluate the finding and significance of ultrasound study. The serults were as follows; 1. There were variableentities of diseases including 16 cases of Baker's cysts, 8 cases of abscesses, 8 cases of neoplasms, 4 cases ofhematomas and each case of joint effusion and bursitis, ganglion, thickening of soft tissue, muscle rupture andforeign body, respectively. 2. Baker's cyst was possibly diagnosed by characteristic site and finding withclinical history. 3. Abscess and hematoma showed hypoechoic or anechoic mass. Hematoma was easily diagnosed byassociated findings with trauma, such as muscular swelling and rupture or bony fracture, but it was difficult todistinguish abscess from neoplasm due to similar finding. 4. Ultrasonography was a modality not only accurate fordetermining the presence, size and localization of lesions, but also easy for defining cyst or solid nature andrelationship between lesions and adjacent structure.