From January 1986 to February 1993, 85 patients with spontaneous pneumothorax were treated in our department by a new endoscopic procedure using an Nd-YAG laser beam via thoracoscopy to obtain permanent pleurodesis and to treat the lung lesion responsible for the air leak. The 55 men and 30 women ranged in age from 16 to 51 years (mean age 26 years). Under general anesthesia the thoracoscope was introduced through a 1-cm incision in the anterior axillary line of the fourth intercostal space. In 68 patients small blebs (less than 2 cm in diameter) were detected and successfully resected with low power Nd-YAG laser pulses. In two patients found at thoracoscopy to have lesions larger than 2 cm, the Nd-YAG laser failed to seal the air leak and thoracotomy was performed. Air leaks were not detected at endoscopy in the remaining patients. After treatment of the lung lesions, the parietal pleura was abraded by using the laser energy. There were no side effects. Eighty patients were treated successfully without recurrence (maximum follow-up 86 months). Three other patients developed recurrence of pneumothorax after 5, 6, and 24 weeks, and surgery was considered mandatory in 2 of them. At thoracotomy, in both patients, a small bleb was detected in the lower lobe and resected. The whole upper lobe was strongly adherent to the parietal pleura in the site of previous laser abrasion. The authors conclude that Nd-YAG laser via thoracoscopy should be considered as a viable therapeutic option in patients with spontaneous pneumothorax.