Contrast enhanced ultrasound (CEUS) is already well estabilshed in the diagnosis of liver lesions. This retrospective Study investigates the value of contrast enhanced ultrasound as a diagnostic tool for lesions of the thoracic wall and for mediastinal tumors. The aim was to reveal criteria that will allow to differentiate between malignant lymphoma, malignant non-lymphatic Tumors and benign lesions as well as between malignant and benign lesions. 40 patients with mediastinal tumors (5 benigne, 25 lymphoma and 10 nonlymphatic tumors) and 66 patients with tumors of the thoracic wall (24 benigne, 8 lymphoma and 34 non-lymphatic tumors) were included. CEUS was performed on all of these patients using the following criteria: 1. time to contrast enhancement (TE) of the tumor, 2. extent of contrast enhancement (EE) in the arterial and the parenchymal phase (determined as isoechoic, hypoechoic and anechoic), 3. homogenity of contrast enhancement (HE) (homogeneous versus inhomogeneous). For evaluation of EE and HE the tissue enhancement of the spleen was used as an «in-vivo-reference». A second generation contrast agent, SonoVue ® (Bracco SpA, Milan, Italy) was used. Using these criteria no significant difference could be seen for malignant and benigne lesions of the mediastinum as well as for the thoracic wall regarding TE, EE and HE. A subgroup analisis oft he mediastinal lymphomas could not show a differece between Hodgkin-Lymphoma and Non-Hodgkin-Lymphome too. Regarding the lesion of the thoracic wall 12 (50%) of the benigne lesions and only 2 (5,9%) of the malignant lesion showed no contrast-enhancement. This was a high significant difference (p<0,001). The negative predictive value was 0,86. That means that a lesion of the thoracic wall with absence of contrast enhancement has a presumption of 86 % to be not malignant. Summing up contrast enhanced Ultrasound (CEUS) is not able to differ the etiology of mediastinal Tumors. In the diagnosis of chest wall lesions characteristic pattern of the different etiologies could not be found. But there is a possibility to differ between benign and malignant Tumors.