Abstract. The present study was conducted to determine the effect of a low dose of human chorionic gonadotropin (hCG) on the induction of fertile estrus in Shiba goats pretreated intravaginally with progesterone during the early postpartum period. Nursing Shiba goats (n=13) around 3 weeks after the parturition were pretreated with a controlled internal drug release dispenser (CIDR) containing 0.3 g of progesterone for 7 day, and 60 µg of cloprostenol 24 hr before CIDR removal. Goats in Group I (n=6) received subcutaneous injections of a low dose of hCG (1 IU/kg) after the removal of CIDR at 12-h intervals until the occurrence of estrus. Goats in Group II (n=7, control) received subcutaneous injections of saline instead of hCG. The rate of estrus induction in Group I (83.3%) tended to be higher than that in Group II (42.9%), although the difference was not significant (P=0.14). Time from the removal of CIDR to the beginning of estrus in Group I was significantly shorter than that in Group II (P<0.05). A prominent peak of estradiol-17β concentration in plasma was observed with a maximum value at 30 h after the removal of CIDR in Group I, while two relatively small rises were detected with a maximum value at 48 h in Group II. The pregnancy rate in Group I (83.3%) was significantly higher (P<0.05) than in Group II (28.6%). These results suggest that the injections of low dose hCG after the treatment with CIDR promote follicular maturation and fertile estrus induction in the goats during the early postpartum nursing period. Key words: Low dose hCG, Estrus induction, Goat, Postpartum nursing period, Estradiol-17β (J. Reprod. Dev. 48: [497][498][499][500][501][502][503][504] 2002) hiba goats originated from a Japanese native dwarf breed and are known to be continuous breeders [1]. The Shiba and other dwarf goats have b een u s ed fo r va ri o us r es ear c h es , s u ch as r epr od uct ive phys io logy and pat ho log y of ruminant [2,3], physiology of fetus [4], cloning of animals [5], and thus recent demand for the goat has been expanding. In order to improve the reproductive efficiency of the Shiba goat, the interval from parturition to conception needs to be shortened. In cattle, ovaries are acyclic in the early postpartum period mainly due to the inadequacy of pulsatile release of luteinizing hormone (LH), but not follicle-stimulating hormone (FSH), due to calf nursing and/or negative energy balance [6]. Therefore, it is thought that treatment with hormones possessing LH activity might mature antral follicles and induce fertile estrus in acyclic animals during the early postpartum period.It has been reported that, in immature rats, a low