IntroductionPrimary spontaneous pneumothorax (PSP) usually occurs in young, tall, and lean men, especially smokers with no obvious underlying lung disease. It arguably results from rupture of subpleural blebs or bullae. The most frequent complication of PSP is recurrence, which is estimated to occur in 20% to 60% after conservative treatment (1,2). More than 50% of patients with PSP have contralateral blebs/bullae and about a quarter will develop contralateral pneumothorax (3). The British Thoracic Society (BTS) guidelines include first recurrence of contralateral pneumothorax and synchronous bilateral PSP as the only indications for surgery of the contralateral lung (4). However, surgery of the contralateral lung to prevent possible complications remains controversial (5-7). To date, only few studies on small populations have discussed both ipsilateral and contralateral recurrences of PSP. The purpose of our study was to identify the predictors of ipsilateral and contralateral recurrences of PSP and to review literatures on the association of blebs/bullae on high resolution computed tomography (HRCT) of the chest with PSP recurrence. Knowing the risk factors for PSP recurrence may enable us to optimize patient selection to avoid further recurrence and complications.