The etiological investigation of spontaneous pneumothorax (SP) is not standardized, and the role of chest CT in this indication remains controversial. The aim of our study was to determine the etiological profile of SP and to identify the role of chest CT in determining the etiology of this condition.Prospective and descriptive study involving patients hospitalized for PS at the Pneumology Department of Mohamed Taher Mâamouri Hospital in Nabeul between August 2013 and December 2019.Our study included 206 patients. PS was classified as primary spontaneous pneumothorax (PSP) in 132 cases and secondary spontaneous pneumothorax (PSS) in 74 cases. In the PSP group, chest CT scans were performed in 93 patients (70.4%), and revealed infra-radiological abnormalities such as pulmonary emphysema in 52.7% of cases. In the PSS group, CT scans were carried out in 70 patients (94.6%), identifying abnormalities such as blebs or emphysema in 44.3% of cases that were not visualized on the chest X-ray. Chronic obstructive pulmonary disease with pulmonary emphysema topped the list of PSS etiologies.