Only the exact pretherapeutical, histopathological diagnosis of non-distinctive soft tissue tumours leads to adequate therapy. Next to the standardized incisional biopsy, current needle biopsy techniques are limited by the small size of the tissue samples and error rate. This study was performed to explore whether the ultrasound-guidance can support the vacuum-assisted biopsy of soft tissue tumors in technical safety. Between 2004-2006, 116 patients with non-distinctive soft tissue tumours underwent ultrasound-guided vacuum-assisted biopsy (uVAB). The results were compared to a cohorte with standardized incisional biopsy (IB). The procedure was successful in 115 patients (success rate: 99,1%). Rate of complications was 4,3% (n=5/116). This closed biopsy technique was performed as an outpatient procedure with local anaesthesia. Diagnosis by uVAB was comparable to the control group (concordance of entity in 94,7%, grading: 89,3%, sensitivity: 93,5%, specificity: 100%, accuracy: 96,2%). Ultrasound-guided the vacuum-assisted biopsy is a safe procedure for soft tissue tumors. The results of this minimal invasive method are comparable to open the gold-standardized incisional biopsy.