Video-assisted thoracic surgery is an important component of modern thoracic surgery, providing a safe, less invasive alternative to open thoracotomy in the evaluation of pleural, mediastinal, and parenchymal pathology. Advancements in endoscopic techniques and video-optics have permitted greater visualization of the thoracic cavity and allowed limited pulmonary resections with significantly reduced postoperative morbidity. Thoracoscopy is indicated for diagnosis of intrathoracic pathology when usual methods of diagnosis, including fine-needle aspiration and transbronchial biopsy, are inconclusive. The diagnostic accuracy of video-assisted thoracic surgery approaches 100%. Increasingly, the indications for thoracoscopy include therapeutic resections of pulmonary nodules in cases of limited lung metastases and bronchogenic carcinoma when pulmonary function is poor. Successful diagnostic and therapeutic resection by thoracoscopy requires intraoperative localization of the lesion within the collapsed lung. The indications and methods of thoracoscopic surgery and preoperative localization are discussed.