Review of a large group of patients treated for spontaneous pneumothorax has revealed a progressively higher incidence of recurrence in the three periods studied, covering a span of seventeen years. During this time the immediate management of this entity has changed from simple bedrest plus occasional thoracentesis to the routine use of closed thoracostomy with water-seal suction drainage. Definite indications for operation have become established and include the following: (1) failure of prompt and complete re-expansion after closed thoracostomy; (2) one or more ipsilateral recurrences; (3) single recurrence with bilateral apical blebs; (4) simultaneous bilateral pneumothorax; (5) asynchronous bilateral pneumothorax; (6) single episode with apical lung cyst; (7) continued intrapleural bleeding.