BACKGROUND: The aim of this study was to investigate etiologic factor, treatment, prognosis of spontaneous pneumothorax(SP). MATERIAL AND METHODS: The medical records of 225 cases of SP experienced at Kyungpook University Hospital from Jan. 1996 to Dec. 1997 were retrospectively analyzed. RESULTS: 1. The patients were 128 primary SP and 97 secondary SP. The mean age was 30 +/- 15.5 years in primary SP and 51 +/- 7.4 years in secondary SP. 2. The ratio of male to female was 8 : 1 in primary SP and 5.5 : 1 in secondary SP. Smoker was more common in secondary SP (71.1%) than primary SP(34.4%). About 70% of patients with primary and secondary SP was underweighted. 3. The previous history of SP was present in 28.9% and 25.8% of primary and secondary SP, respectively. 4. The main underlying lung diseases in secondary SP were inactive tuberculosis(68%), active tuberculosis(12.4%) and COPD(11.3%). 5. Tube thoracotomy was performed in 96.8% and 97.9% of primary and secondary SP, respectively. The duration of chest tube insertion was longer in secondary SP (18.2 +/- 19.59 days) than primary SP (7.5 +/- 6.57 days). 6. The open thoracotomy were performed in 22.7% and 10.3% of primary and secondary SP, respectively. The most common indication of open thoracotomy was recurrence on primary SP and persistent air leak in secondary SP. 7. During following-up of 17 +/- 7.8 months, the recurrence rate on patients with conservative treatment was 16.5% and 11.8% of primary and secondary SP, respectively. The recurrence was most common within 1 month after discharge. CONCLUSION: Greater attention and research about SP are necessary for more efficient patient care.