The Purpose of this study was to observe the body temperature changes of newborn infants in general crib and electric-heat crib after birth for the period required to reach the optimum body temperature. Forty-seven newborn infants who were delivered at Seoul National University Hospital during the period from June 12 to September 13, 1973 were chosen as Subjects for this study. The criteria for the choice of subjects were the babies with normal spontaneous delivery; body weight 2. 5㎏ and over at birth; Apgar score seven and over and gestation period over thirty-six weeks. Of these subjects, by random sampling thirty-one newborn infants were placed in the general crib and sixteen in the electric-heat crib. The rectal body temperature of these newborn infants were taken and recorded at fifteen-minute interval for the first one hour period after birth, at thirty- minute interval for the next two hours and at one-hour interval for the remaining period up to eight hours. The results of the study were as follows: 1. The mean body temperature of the newborn infants on admission to nursery ranged from 98.7°F. to 99°F. irrespective of the body weight and the room temperature. 2. There was a significant difference in the body temperature changes of the newborn infants as a total between the general crib and the electric-heat crib from three to eight hours after birth. It was found that the body temperature of the newborn infants in the electric-heat crib was significantly higher than that of the newborn infants in the general crib. 3. In comparison with the body temperature changes of the newborn infants in the general crib, the newborn infants in the electric- heat crib exhibited significantly higher body temperatures in all three body weight groups; from four to eight hours after birth in the 2.5-2.9㎏ body weight group; from three to seven hours after birth in the 3.0-3.4㎏ body weight group; from two and half to six hours after birth in the group with body weight over 3.5㎏. 4. Time required to reach 98°F. of body temperature was four hours in the 2.5-2.9㎏ body weight group, three hours in the 3.0-3.4㎏, body weight group and two and half hours in the group with body weight over 3.5㎏ in the electric- heat crib. In the general crib, it took over eight hours in the 2.9㎏ body weight group and five hours in both the 3.0- 3.4㎏ and over 3.5㎏ body weight group to reach 98°F of body temperature. 5. The lowest mean body temperature of newborn infants in both general and electric- heat crib appeared in forty-five minute after birth and the temperature ranged from 96.4°F to 96.5°F. 6. The mean body temperature of the newborn infants in the general crib was increased as the room temperature. 7. The body weight, the room temperature and the time elapsed alter birth were proved to be significant factors influencing the body temperature changes of newborn infants. From the above results, the three hypotheses were positively accepted.