We analyzed the sonographic appearance of the ribs when there was tumor involvement in 16 patients (12 men and 4 women). The tumors included 11 carcinomas, 3 nonepithelial malignancies and 2 benign tumors. Three sonographic patterns on the cross section of abnormal ribs were identified. Pattern I was an eccentrical hyperechoic plate-like shadow inside a hypoechoic tumor. Pattern II was a round hyperechoic shadow or ring in the center of a hypoechoic tumor. Pattern III was a hypoechoic tumor only. The Pancoast tumor manifested pattern I. Metastatic cancer, mostly squamous cell carcinoma, manifested pattern II, and both malignant and benign tumors could manifest pattern III. In sonography, the margin and shape of the tumors, the change in the acoustic shadow of the rib and the pleural line did not differentiate the malignant tumors from benign tumors. When we routinely took a biopsy of these tumors under sonar guidance, the diagnostic yield was 100% without any complications. We conclude that the rib should be evaluated in chest sonography, and that pattern recognition and biopsy under sonar guidance are most useful.