These experiments were carried out to obtain the fundemental information essential for the induction of superovulation in cattle. The effects of parity, season and the source of gonadotropins on ovarian response to gonadotropins given for superovulation were investigated. The results obtained in these experiments were summarized as follows: 1. Of 43 donor cattles treated with PMSG to induce superovulation, 86.0% responded with 2 or more corpora lutea and 55.8% with 6 to 13 corpora lutea. 2. No differences in ovarian response to PMSG administration among breeds were observed. 3. Average numbers of corpus luteum per donor cattle following PMSG administration in heifers, 1-2, 3-4 and 5 or more calved cows were 6.4, 9.3, 6.4 and 5.3, respectively. 4. No seasonal variations in ovarian response to PMSG given to induce superovulation were observed. 5. There were no significant differences in numbers of corpora lutea between the donor cattles treated with PMSG and FSH, respectively.