There are several methods for managing pneumothorax through thoracoscope. Among them, electric cautery of bleb or bulla is very simple to do and can be done through the conventional thoracoscope. It is cosmetically excellent because it needs only incision. It is economically cheap comparing other methods because it does not need staplers or clips and other disposables. However, this method has been controversial for its success rate because of the ability of sealing off the air-leaking from the lung tissue. To evaluate the success rate, 29 cases of pneumothorax treated by electric cautery and instillation of oxytetracyline solution through the thoracoscope were analyzed. Among 29 patients, 18 were male and 11 female ranging 17 to 43 years old. The indications for thoracoscopy were recurrence in 20 cases and persistence in 9 cases. The underlying casuses of pneumothorax were bleb in 10 cases and bulla with bleb or not in 19 cases. Twenty one cases were successful [4%] and 8 cases were failed. The failed 8 cases were explored from 14 to 28 days after thoracoscopy.Six cases were explored through transaxillary minithoracotomy and 2 were done through limited posterolateral thoracotomy. The causes of failure were the necrotic lung tissue occured by excessive electric cautery in 6 cases and the necrotic lung tissue and residual bulla in two cases. In 10 bleb cases, 9 were successful [90.0%]. But in 19 cases of bulla, 12 were successful [63.2%]. In conclusion, the success rate of electric cautery through thoracoscope was 72. 4% and the causes of failure were lung necrosis and residual bulla. The success rate of the bleb cases was higher than that of the bulla cases.