The records of 121 patients who underwent surgical thoracoscopy between 1976 and 1987 were reviewed. The indications for thoracoscopy were pleural effusion (88%), pleural thickening (7.4%), and a mass on the chest roentgenogram (15%). All procedures were performed under general anesthesia with a rigid thoracoscope and 91 patients (75%) were diagnosed as having a malignant process. Although thoracotomy was undertaken in 20 patients (16.5%), no patient with benign disease underwent diagnostic thoracotomy. Thoracoscopy had a 98.9% sensitivity and a 93.3% specificity in this series. One patient died of a myocardial infarction after the procedure, and 11 patients (9.1%) had other, predominantly respiratory, complications. We confirm that surgical thoracoscopy is a useful procedure in the diagnosis of pleural processes.