PURPOSE: To compare perinatal characteristics, clinical courses, and overall morbidity between respiratory distress syndrome(RDS) with patent ductus arteriosus(PDA) and RDS without PDA in neonates. METHODS: Eighty-three neonates who were diagnosed and treated for RDS in the neonatal intensive care unit(NICU) from Jan. 2000 to Dec. 2002 were included in this study. RDS was complicated with PDA(group A) in 17 patients and not complicated in 66(group B). PDA was diagnosed by echocardiogram in neonates with congestive heart failure symptom, cardiac murmur or chest X-ray findings of cardiomegaly or pulmonary edema. A retrospective study was undertaken of the perinatal charac teristics and overall morbidity in group A and group B. RESULTS: The birth weight and gestational periods of group A were less compared with group B. There was more perinatal asphyxia in group A. Incidence of overall morbidity such as bronchopul monary dysplasia, intraventricular hemorrhage and death was higher in group A. Intravenous indomethacin was administered in 17 PDA infants. CONCLUSION: The perinatal characteristics in the two groups showed a significant difference. Incidence of overall morbidity in the two groups showed significant differences, however, there is no simple conclusion to draw because we didn't do multifactorial analyses to rule out other many risk factors affecting morbidity, such as gestational weeks or birth weight.