In this study, 26 cases of bilateral spontaneous pneumothorax experienced at the department of thoracic and cardiovascular surgery, Chungnam National University Hospital during from 1985 to August 1989 were analyzed retrospectively. The results were as follows; 1. The incidence of bilateral spontaneous pneumothorax was 13.5 % and sex ratio was 7.7:1 with male preponderance. 2. Among the nonsimultaneously occurring cases of bilateral pneumothorax, 12 patients [75 %] were developed at contralateral side within a year. 3. The most patients [65.4%] belonged to the age group between 15 and 25 year-old, and among 57 male patients suffered spontaneous pneumothorax in the same age group, 16 cases[28%] developed bilaterally. 4. The etiologic factors were as follows; blebs or bullae; 65.4 %, tuberculosis; 15.4 %, unknown; 19.2 %. 5. In the method of treatment, 15 patients were treated by closed tube thoracotomy and underwater-seal drainage only, 10 patients were treated by open thoracotomy. One patient died of respiratory failure due to severe destructed lung.