To determine the risk factors, clinical presentation, and long-term outcome of primary spontaneous pneumothorax (PSP), all available cases of PSP in the Israeli Defense Forces (IDF) were retrospectively reviewed. Using the computerized IDF database, all men who had pneumothorax were identified and a telephone interview obtained with 343 individuals, 286 of whom had PSP and agreed to participate in this study. These 286 persons experienced 498 episodes of PSP, with 314 medical records available for review. Average length of follow-up from the first episode of PSP was 107.2 months. Of the study population, 11.5% had a positive family history for PSP. The height-to-weight ratio was significantly and positively correlated with the number of PSP episodes per person, with the regression coefficient being 0.49. The age distribution of those with PSP had a monophasic pattern, with the average age being 25.3 years on first episode. More than one episode of PSP occurred in 41.3% of patients. No ipsilateral recurrences were observed after surgery. Treatment with a sclerosing agent seemed to be more effective in preventing ipsilateral recurrences of PSP than chest tube insertion alone (26.5% vs. 38.3%). Primary spontaneous pneumothorax is an important medical problem, especially in men of military age. It has a significant inherited component in its etiology, with asthenic body build being an additional risk factor. Based on a literature review and the data obtained from this study, it was concluded that chest tube insertion with intrapleural instillation of a sclerosing agent is the preferred nonsurgical invasive treatment modality in PSP.