Forty neonates with respiratory distress syndrome were transferred from nursery after birth to the ICU at Severance Hospital, Yonsei Medical Complex between March 1981 to July 1983 and ventilatory support was given with the pressure-cycled ventilator, Babylog l, Bourns BP 200, in ICU. We have analysed the 40 cases according to sex, incidence, symptoms and signs, birth weight and gestation weeks and time to the ventilator support, ICU days and mortality. The results were as follows 1) The proportion of the patients was 0.7% neonates and the overall mortality was 52.5%. 2) Obstetric and delivery background were as follows. Ceasarean section, 19 cases: pre-eclampsia, 5 cases: placenta-previa, 5 cases: spontaneous premature rupture of membrane: 4 cases. 3) The percentage and mortality of male patients was 52.5% and 57.1%, higher than female patients. 4) All the patients showed symptoms and sings within 12 hours after birth. 5) Mortality of those cases born with less than 32wks gostation was 15%, but above 32wks the mortality was 35%. 6) The number of babies born with a birth weight below 2,000 grams was 27 and the mortality for them was 70%. 7) The number of cases who had ventilator support begun at 10 hrs, 11~20 and 21~30hours after symptoms and sings developed, were 30, 5 and 5. The mortality was 53, 20 and 60% respectively for these 3 groups. 8) The number of ventilator days less than 4 days duration was 27 cases with a 70% mortality but those above 5 days was 13 cases with 16% mortality. in 1981, the number of patients with ventilator days less than 2 days was 11 cases and 2 cases used the ventilator for 7~8 days. But in 1983 the number of patients with less than 4 ventilator days was 6 cases, and 7cases used ventilator for more than 5 days. 9) The number of patients with ICU days less 5 days was 23 cases and a mortality of 78% and those of 6~10day stay was 6 cases with a mortality of 50%. The number of patients with ICU days above 15 days was 18 and all survived. In 1981, 10 cases stay in the ICU for less 5 days. Only 2 cases stayed in the ICU for 6~10 days. In 1983, 6 cases stay in the ICU for less 5 days, but 4 cases stayed in the ICU for more than 15 days. 10) Complications were neonatal hyperbilirubinemia, pneumothorax, pneumomediastinum, sepais, disseminated intravascular coagulopathy, bronchopulmonary dysplasia, and cerebreal hemorrhage. From the above results the mortality rate decreased year by year and this is attributed to the early application of ventilator support and adequate intensive care.