We evaluated the usefulness of thoracoscopic ultrasonography for diagnosing intrapulmonary nodules. We studied 7 patients undergoing thoracoscopic operations. Three had benign lung tumors, one had metastatic lung tumors from a renal cell cancer, and three had primary lung cancers. During thoracoscopy three benign tumors were seen as masses protruding from the visceral pleura in to the pleural space, and two primary lung cancers were seen as pleural indentations. However, the presence of one metastatic lung tumor and one primary lung cancer could not be confirmed by thoracoscopy because of the lack of pleural changes. Furthermore, intrapulmonary spread of malignant tumors in four cases could not be seen by thoracoscopy. All tumors were seen clearly and their characteristics were identified by thoracoscopic ultrasonography. Partial lung resection during thoracoscopy was successful in all patients. We found thoracoscopic ultrasonography to be useful for confirming the presence of peripheral solid nodules, and for deciding where to make incisions for partial lung resection.