The aim of our study was to evaluate the role of ultrasonography in the localization of pulmonary nodules during video-assisted thoracic surgery (VATS). Ultrasonography was performed in 35 patients for the localization of pulmonary nodules during VATS. Indication for VATS was excisional biopsy of undetermined nodules in 22 patients, single or multiple metastasectomy in 12 patients and resection of primitive pulmonary cancer in 1 patient with reduced pulmonary reserve. A laparoscopic probe with flexible head and multi-frequency transducer (5-7.5 MHz) was used. Intraoperative ultrasonography localized 37 of 40 nodules preoperatively detected by CT and/or by positron emission tomography in 35 patients. Furthermore, ultrasonography localized two nodules not visualized at spiral CT. Eighteen nodules were not visible or palpable at thoracoscopic examination and were found by intraoperative sonography only. In 6 patients in whom thoracotomy was performed, manual palpation did not reveal more lesions than ultrasonography. In our experience, ultrasonography was very helpful when lesions were not visible or palpable during thoracoscopy, showing high sensitivity (92.5%) in finding pulmonary nodules. Since it is not possible to determine preoperatively whether a localization technique will be necessary during the operation or not, and ultrasonography is a non-invasive technique, we think that, at present, this technique can be considered as the first-instance localization technique during thoracoscopic resection of pulmonary nodules.