PURPOSE: Pneumothorax is an important factor responsible for increased mortality and morbidity in neonates. Here, we compared the clinical findings and prognosis for neonatal pneumothorax induced by respiratory distress syndrome (RDS) and pneumonia. METHODS: Between January 2001 and December 2005, 80 patients with neonatal pneumothorax induced by RDS and pneumonia and admitted to the NICU of Dongsan Medical Center, Keimyung University, were enrolled. They were assigned to the RDS group (30 cases) or the pneumonia group (50 cases). Admission records for gestational age, onset day of life, rate of ventilatory care and thoracostomy, and prognosis were retrospectively reviewed and statistically analyzed for both groups. RESULTS: The mean gestation age was significantly shorter in the RDS group (32.3 weeks) than in the pneumonia group (38.1 weeks) (P<0.001), and the mean onset day of life were later in the RDS group (4.6 days) than in the pneumonia group (1.8 days) (P<0.05). Rates of ventilatory care and thoracostomy were higher for the RDS group than for the pneumonia group (100% vs. 44%, and 66.7% vs. 48%, respectively). Total mortality rates and pneumothorax specific mortality rates were higher for the RDS group than for the pneumonia group (46.7% vs. 18%, P<0.01 and 33.3% vs. 16%, P<0.05, respectively). After logistic regression analysis, preterm significantly increased the mortality rate (OR 7.44, 95% CI: 1.99-27.86, P<0.005), but bilateral involvement (OR 1.17, 95% CI: 0.82-1.67, P>0.5) and the RDS group itself (OR 1.70, 95% CI: 0.52-5.54, P>0.3) did not increase mortality rates significantly. CONCLUSION: Our study suggests that neonatal pneumothorax in the RDS group tends to have a later onset, higher mortality rate, and needs a higher rate of thoracostomy than the pneumonia group. However, after logistic analysis, only preterm significantly and independently increased the mortality rate.