Before operation, we evaluated the usefulness of ultrasonically guided needle biopsy to detect histologically invasion of the chest wall by tumor in patients with lung cancer. Ultrasonically guided needle biopsy, computed tomography, and ultrasonography were done in 29 patients with lung cancer. In all of them, chest wall invasion was histologically confirmed by thoracotomy. As for the diagnosis of chest wall invasion, sensitivity, specificity, and accuracy of ultrasonically guided needle biopsy diagnosis were 61.5%, 100%, and 82.8%, respectively; for diagnosis by computed tomographic scan these figures were 69.2%, 75.0%, and 72.4%, respectively; and for diagnosis by ultrasonography they were 76.9%, 68.8%, and 72.4%, respectively. We had no false-positive cases in the ultrasonically guided needle biopsy assessment and no fatal complications or implantation metastases. Our results indicate that ultrasonically guided needle biopsy is safe and useful for preoperative histologic diagnosis of chest wall invasion in cases in which combined chest wall resection is being considered in patients with lung cancer.