BACKGROUND Pneumothorax is one of the air leak syndrome and is more common in the newborn period than in any other childhood periods. It can be divided into spontaneous pneumothorax and secondary pneumothorax from underlying lung pathology or assisted ventilation. Pneumothorax results in longer hospital stays and even deaths in some cases. To date, there are few studies that focus on identifying risk factors of pneumothorax. We conducted this study to ascertain risk factors for pneumothorax, in order to create a guideline to prevent this condition. METHODS This is a retrospective case-control study. CASEs were infants with the diagnosis of pneumothorax (P25.1 Pneumothorax originating in the perinatal period) between January 2001 and December 2004. Controls were those whose birth times followed in the immediate chronology to the cases. METHODS control ratio was 1:2. Univariate analysis was used to compare the two groups. Odds ratio and 95% confidence interval were used to identify possible risk factors. Statistical significance was considered as p < 0.05. RESULTS There are 44 cases and 88 controls. Risk factors are shown as Odds ratio and 95% confidence interval. Infant factors associated with higher risk of pneumothorax are male (2.6; 1.2, 5.6), low birth weight (19.3; 2.3, 160.2), vacuum extraction (20.9; 1.1, 403.4), meconium-stained amniotic fluid (4.5; 1.8, 11.0), low 1-minute Apgar score (78.3; 4.5, 1357.8), and the administration of bag and mask positive-pressure ventilation (29.0; 3.6, 233.5). Maternal factor associated with higher risk of pneumothorax is poor antenatal care (3.5; 1.04, 11.9). CONCLUSIONS All pregnant women should be encouraged to have good antenatal care. Mother who has complication(s) during pregnancy and delivery should receive special care to prevent perinatal depression. For mothers with meconium-stained amniotic fluid, close fetal monitoring and tracheal suction for meconium after delivery should be appropriately considered to prevent meconium aspiration. Finally, neonatal resuscitation, when needed, should be done very carefully by following the American Heart Association and the American Academy of Pediatrics guidelines, especially for bag and mask positive-pressure ventilation.