This study was conducted to find out the changes of progesterone and estradiol-17$eta$ levels in the serum of female Korean native goats during the reproductive stages such as the estrous cycle, pregnancy and periparturient period. Nine heads of female Korean native goats of 3 year old in average and weighing 35.7$pm$1.4 kg were offered for the experiment. Blood samples were taken at 0, 1, 2, 5, 7, 10, 13, 15, 18 and 19 days after onset of estrus, and 1, 30, 60, 90, 120 and 149 days of pregnancy, and -5, -2, -1, 0, +1, +2 and +5 days of periparturient period where minus figures denote the days before paturition. The progesterone, estradiol-17$eta$ in the serum samples were assayed by radioimmunoassay methods. The results of this study are summarized as follow: 1. The progesterone levels during the estrous cycles reached a peak level of 0.98$pm$0.60ng/ml at 13 days after onset of estrus and decreased thereafter and were lower than 0.09$pm$0.02mg/ml on the first day of estrus. 2. The estradioe17$eta$ levels during the estrous cycles showed a peak level of 15.97$pm$1.72pg/ml at onest of estrus, and decreased (5.41$pm$0.51pg/ml-9.09$pm$1.82pg/ml) during luteal phase. 3. The progesterone levels during the gestation period increased from day 1 and peaked at 90 days after mating and then decreased until 149 days. The peak level was 6.27$pm$0.23ng/ml at 90 days. 4. The estradiol-17$eta$ levels during the gestation period showed gradual increase, which were 9.03$pm$0.88, 32.96$pm$2.85, 46.03$pm$2.42, and 54.06$pm$1.64pg/ml on 30, 60, 90 and 120 dyas after mating respectively. 5. The progesterone levels measured from 5 days before the parturition to 5 days after showed the highest level at the shart of measurement (4.46$pm$0.31ng/ml) and decreased gradually and bottomed out at one day post-partum and thereafter (0.24$pm$0.02-0.45$pm$0.06ng/ml). 6. The estradiol-17$eta$ levels measured during the same periparturient period as progesterone showed increase to reach the peak level at 1 day before parturition and decreased rapidly thereafter (-5 dyas 69.46$pm$3.62, -2 days 107.07$pm$1.91, -1 days 137.83$pm$7.54, 0 days 50.06$pm$6.71 and +1 to +5 days 3.21-4.72 pg/ml).