['One cause of recurrent spontaneous pneumothorax includes overlooking bullae during a previous surgery for pneumothorax; and the identification of the culprit lesions is necessary for prevention of recurrence.', 'A 28-year-old man was referred to our hospital because of spontaneous right-sided pneumothorax. He underwent video-assisted thoracoscopic surgery, which did not reveal air leakage. The patient was subsequently seen at our hospital for 2 additional episodes of recurrent right-sided pneumothorax. At the third admission we observed intermittent air leakage while the patient was in the sitting position after chest drainage, and we performed surgery. An intraoperative submersion test showed air leakage dorsally from the pleural surface of S(6) and a minute culprit lesion, which were not seen at the first operation and confirmed the leakage site. The area was ligated and coated with regenerated oxidized cellulose mesh and autologous blood.'] Is the best time for surgery on a patient with recurrent pneumothorax and undetectable culprit lesions at the exact time air leakage is discovered : a case report?