The present study was conducted to find out the changes of progesterone and 20$alpha$-dihydroprogesterone(20$alpha$-OHP) levels during the gestation period in Korean native goats. 4 pregnant goats were offered for this experiment. Blood samples were taken from jugular vein on Day 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140 and 145 of the pregnant goats. The serum levels of progesterone and 20$alpha$-OHP were measured by radioimmunoassay. The progesterone level in goat serum during the gestaton was low as 2.94$pm$0.21 at 5 days, and then increased to 4.51$pm$0.25ng/ml at 10 days of gestation and increased greatly from Days 60 and reached a peak level of 7.21$pm$0.58ng/ml at 100 days of gestation, and thereafter decreased to 6.01$pm$0.57, 5.26$pm$0.64ng/ml on Days 130, 140 of gestation, and decreased to 4.05$pm$0.52ng/ml on Days 145 of pregnancy. The serum level of 20$alpha$-OHP during the gestation was low as 0.3~0.4ng/ml in the early stage of pregnancy, and increased gradually and increased to 0.85$pm$0.06ng/ml, 0.97$pm$0.08ng/ml on Days 90 or 100, and then increased to 1.18$pm$0.18, 1.25$pm$0.21ng/ml on Days 140 or 145 of gestation. While the serum levels of progesterone during the luteal regression decreased, the 20$alpha$-OHP increased continuously. From the above results, it was concluded that the enzyme 20$alpha$-hydroxysteroid dehydrogenase (20$alpha$-HSD) catalyzing theconversion of progesterone to a biologically inactive steroid, 20$alpha$-OHP was active properly in the luteal cells what the levels of progesterone decreased and the levels of 20$alpha$-OHP increased during the late pregnancy in Korean native goats.