We took clinical observation for low-birth-weight infant who had been delivered at Chosun University Hospital during the last 4 years from July, 1972 to June, 1976. The results obtained were as follows; 1) High incidence of low-birth-weight infant was found in group of gestational period, 31-33 weeks and birth weith, 1501~1750 gm . and those were 16 cases. 2) The incidence of low-birth weitht infant was 8.4% and there was no different distribution between male and female. 3) Incidence of low-birth-weight infant by maternal age was in order of the group of 26-30 years old, the group of 20-25 years old and the group of 31-35 years old and the incidence by parity was higher in multiparity than in primiparity. 4) Incidence of low-birthpweight infant by the type of delivery was in order of normal vaginal delivery, breech delivery and C-section delivery. 5) Etiology of low-birth-weight infant was in order of multiple pregnancy, toxemia, placenta previa and abruptio placenta, premature repture of membrane and congenital syphilis. 6) Mortality rate by weight-gestational age was lower in the group of apprepriate for gestational age infant than in the group of small for gestational age infant and in the group of large for gestatonal age infant. 7) Higher mortality rate was noted in the group of lower birth weight infant, the group of more shortened gestational period and the group of lower Apgar score. 8) Incidence of twin was 11.4% and death was noted only 1 case in male group. 9) In the respect of physiologic weight loss, an average maximal weight loss 9.3% of birth weitht and average maximal weight loss was appeared on 8th day after birth and the duration of returning to the birth weight was 13.5 days. 10) Average body measurements at birth were as follows: head circumference, 30.5cm, length, 43.9cm, and chest circumference, 27.7 cm and there was tendency of lower value of body measurements in the group of lower birth weight. 11) In the chest x-ray which was taken within 12 hours after normal finding was 98 cases (81.0%), hyaline membrane disease. 7(5.8%), atelectasis, 6(5.0%), congenital heart disease, 2(1.7%) and 1 case (0.8%) of pneumothorax. 12) In the peripheral blood cell count, there was higher value of Hb, RBC and Hct in the group of higher weight, but this proportional relationship was not found in WBC count.