Background/Purpose: The aim of this study is to determine factors effecting mortality of pneumothorax in the neonatal period. Method: 87 newborns (29 Female/58 Male) with pneumothorax, who were treated with tube thoracostomy between January 1998 and December 2000, were analysed retrospectively. The patients were evaluated in regard to age, gestational age, weight, primary pulmonary disease other pathologies, ventilatory support, duration of drainage hospital stay after drainage and mortality. Results: The mean age was 48.1±36.5 hours, ranging between 1 hour and 14 days. The main symptoms were respiratory distress, tachypnea and cyanosis. All patients with pneumotorax and mediastinal shifting had been treated with tube thoracostomy 28 patients (32%) needed ventilatory support. The overall mortality was 12.6%. Conclusion: We determined that appearance of symptoms within the first 24-hour, birthweight <2500g, prematurity, existence of a primary pulmonary disease, existence of bilateral pneumothorax and need for mechanical ventilatory support were the factors that had caused high morbidity and mortality rates in newborns with pneumothorax.