Studies on the mechanism of action on intra-uterine foreign bodies are gaining importance in the field of reproductive biology. Doyle & Margolis (1963, 1964a, b) found in the rat that, following ovulation and fertilization, implantation did not occur in the threaded uterine horn due to a hostile uterine environment and interference with the normal decidual reaction. Buch, Shukla & Hawk (1964) showed that in the Surti water buffalo an intra-uterine polyethylene loop prevented ovulation. In cows, Hawk, Conley, Brinsfield & Righter (1964) observed that the loop acted as a contraceptive device within 3 days of breeding, possibly by interfering with one or more of the following processes: fertilization, cleavage, ovum transport and corpus luteum formation.The action of ovarian hormones on the histology of the uterus following ovariectomy has been studied by many workers. Among them, Cleveland (1941) studied the ovariectomized monkey and both Bell, Casida & Darlow (1941) and Ryle (1962) the ovariectomized ewe. Distinct morphological changes due to treatment with ovarian hormones in these species have been established. Oestrogens bring about cell proliferation and the combination of oestrogen and progesterone produces a secretory phase of the endometrium.A trial was performed with seven goats ovariectomized during anoestrus in order to observe the effects of intra-uterine polyethylene spirals, a combination of oestradiol-17\g=b\ and progesterone and their interactions on the histology of the goat uterus.