Although spontaneous pneumothoraces have been recognized and treated for almost 180 yrs, new aspects have emerged concerning pathogenesis, diagnostic procedures and treatment modalities. In spite of the fact that blebs and bullae are frequently found in patients with primary spontaneous pneumothorax, they seldom seem to be the actual cause of the pneumothorax. Inflammatory changes in the distal airways play an important role in the occurrence of the pneumothorax during transpulmonary pressure changes. The value of the routine use of additional expiratory chest radiographs in diagnosing pneumothoraces has been doubted in previous studies. In this review, the diagnostic yield from additional expiratory chest radiographs is analysed. The role of previous pneumothoraces at presentation and the presence of blebs and bullae are discussed in predicting future recurrences and choosing appropriate treatment for optimal cost-effectiveness. Recommendations are made regarding treatment of primary and secondary spontaneous pneumothorax.