Background <p>Pulmonary torsion is an uncommon condition that occurs most frequently after pulmonary resection. Its occurrence in association with spontaneous pneumothorax is very limited. Herein, we report a rare case of pulmonary torsion that developed following chest tube drainage for primary spontaneous pneumothorax.</p> Case presentation <p>A 26-year-old man with a history of chest drainage for right primary spontaneous pneumothorax presented to our emergency department with dyspnea. Chest radiography revealed a right tension pneumothorax, and chest drainage was immediately performed. Chest computed tomography (CT) revealed no apparent bullous disease, but atelectasis of the right middle lobe was observed. Despite the cessation of air leakage, surgical intervention was planned on hospital day 3 because of the recurrence of spontaneous pneumothorax and its presentation as tension pneumothorax. Intraoperatively, the right middle lobe was rotated to the dorsal side of the lower lobe. No congestion or ischemic changes were observed, and detorsion was successfully performed. No obvious bullous disease was detected, though pleural changes at the lung apex were ablated and covered with a polyglycolic acid sheet. The postoperative course was uneventful, and the patient was discharged on postoperative day 4.</p> Conclusions <p>Chest tube drainage for primary spontaneous pneumothorax is a routine procedure widely performed in emergency medicine. Therefore, clinicians must recognize that pulmonary torsion, a potentially fatal complication, can occur unexpectedly in the context of this common procedure. When lobar atelectasis is observed after chest tube insertion, clinicians should consider pulmonary torsion and promptly perform CT imaging.</p>