Respiratory bronchiolitis (RB) is defined by the accumulation of pigmented macrophages in the lumen and wall of respiratory and membranous bronchioles of smokers. The aim of this study was to determine whether spontaneous pneumothorax was associated with a high prevalence of RB. Seventy-nine consecutive patients who underwent a surgical procedure (thoracotomy or thoracoscopy) for recurrence or persistence of primary spontaneous pneumothorax despite thoracic drainage were studied retrospectively. RB was found in 70 of 79 (88.6%) smokers operated for spontaneous pneumothorax. Associated interstitial pathological abnormalities were present in 53 of 79 cases (67.1%). In nine patients, the pathological lesions were severe and resembled desquamative interstitial pneumonia. Emphysematous lesions were present in about one-third of the patients. Although the possible pathophysiological consequences of respiratory bronchiolitis remain speculative, this study demonstrates the high prevalence of this pathological abnormality in patients with pneumothorax requiring surgical treatment.