These studies were carried out to examine the estradiol-17$eta$ levelsin plasma and ovarian tissues, as well as the contents of collagen and catecholamines in the uterus, and to determine the effects of GnRH administrations of uterine involution in postpartum Korean native goats. Plasma concentrations of estradiol-17$eta$ were 63.81$pm$8.00 pg/ml at day 1 of kidding, declined to 36.78$pm$22.90 ng/ml at day 24 and decreased progressively to 27.81$pm$17.06 and 12.46$pm$8.13 pg/ml at days 30 and 36 postpartum, respectively. In ovarian tissues, the concentrations of estaiol-17$eta$ were increased just before parturition and decreased immediately after parturition. The plasma estradiol-17$eta$ levels were slightly higher on days 12 and then decreased gradually after parturition. The concentraitons of estradiol-17$eta$ in the ovaries of postpartum goats were increased at day 36 after treatments with GnRH. The total hydroxyproline contents in the uterus was slightly higher prior to parturition and decreased gradually with the postpartum intervals after parturition. Hydroxyproline concentraitons in the uterus were decreased at days 24 and 36 postpartum after treatments with GnRH. The norepinephrine concentrations in myometrium from the pregnant and postpartum goats were correspondingly low both immediately before and after partuition. Norepinephrine concentrations in the pregnant horn of the uterus were increased from days 12 to 36 of postpartum and those levels of the non-pregnant horn were also increased from days 24 to 36 postpartum. Slightly higher concentrations were present in the non-pregnant horn in comparison to the pregnant horn but these differences were not significant. Postpartum, the uterine norepinephrine concentration was slightly increased at day 36 after treatments with GnRH. Dopamine concentrations were greater than those of norepinephrine. The concentrations of dopamine in the uterus of pregnant goats was not significantly different from that in the postpartum animals. Dopamine concentraitons of pregnant horn in postpartum goats were increased at day 24 after treatments with GnRH.