Two surgical cases of bilateral pneumothorax founded at a medical examination were reported. Case 1; A 15-year-old male was admitted to our hospital pointed out left spontaneous pneumothorax without complaints. The interval between the first and the contralateral pneumothorax was 3 weeks. He was treated with a one-stage operation through a bilateral axillary incision. Case 2; A 19-year-old male was admitted to our hospital pointed out left spontaneous pneumothorax without complaints. Surgical operation was performed with a left axillary incision. One year after the treatment, he was pointed out right spontaneous pneumothorax on his chest X-ray film. Partial resection of the right lung was performed with a right axillary incision. Of the 261 pneumothorax patients, 28 had bilateral pneumothorax in our hospital. The majority of these patients had complaints which were chest pain, dyspnea and cough. Of the 28 patients, 2 had no complaints at the time of admission. We conclude that we have to follow up carefully the patients with hemilateral spontaneous pneumothorax.