Sonography has not been generally accepted as an imaging modality for the evaluation of soft tissue tumors. Three-dimensional ultrasonography appears to be a valuable adjunct to conventional ultrasonography because it provides previously unattainable scan planes and three-dimensional views. This new technique allows to display spatially oriented and standardized views, which reduce the operator dependence and improve the reliability of follow-up studies. 3D data processing provides life like display of anatomy and real time guidance of interventional procedures such as biopsy. 3D ultrasound-guided biopsy can be performed by using multiplanar views or a combination of cross sectional and rendered images. Large core biopsies using a vacuum assisted biopsy device (8G) achieve an accuracy in the histopathological assessment of soft tissue sarcoma that is comparable to incisional biopsy. Improved visualization and guidance of interventional procedures by 3D ultrasound may increase the acceptance of clinicians to use sonography for the evaluation of soft tissue tumors.