Background. To detect chest wall invasion by a tumor is one of the complex diagnostic problems in lung cancer and mediastinal tumors. Moreover, chest X-ray is of low informative value and computed tomography (CT) and magnetic resonance imaging do not always make it possible to diagnose chest involvement. Objective. To improve an ultrasound-guided procedure and to elaborate the semiotics of lung and mediastinal tumor invasion into the chest wall. Subjects and methods. The investigation enrolled 270 patients (168 men and 102 women) aged 14 to 84 years, including 154 (57%) with 116 (43%) with peripheral lung cancer, who had been surgically treated at the P.A. Herzen Moscow Oncology Research Institute in 1992 to 2011. The investigation was performed using the standard ultrasound diagnostic apparatuses. Results. The improved ultrasound-guided procedure and the developed semiotics of chest wall invasions by the invasion by lung and mediastinal tumors could yield the following results: the sensitivity, specificity, and accuracy of the technique were 96.4, 97.6, and 97.4% for mediastinal tumors and 87.5, 91.7 and 90.5% for lung cancer, respectively. At the same time, the sensitivity of ultrasound study was higher than that of CT in both mediastinal tumors (96.4 and 85.2%) and lung cancer (87.6 and 75%) (p<0.01); the difference was statistically significant. Conclusion. In mediastinal tumors and peripheral lung cancer, ultrasound-guided percutaneous study is an effective method to detect tumor nodule the invasion into the chest wall, which can determine the depth of invasion and visualize costal involvement. Comparison of the capacities of this method versus CT has shown that the sensitivity of ultrasound statistically significantly outstripps that of CT. Ultrasound significantly less frequently yielded false-positive results than CT, which is essential when planning surgical treatment.