This study was carried out in order to find out better ways for superovuiation and egg collection by checking some factors affecting on donor cows such as iactating and dried, age, season of treatment and sequence of treatment. The results were summarized as follows:1. Number of corpus luteum and collected eggs of eactating and dried doner were 9.8 vs 8.0 and 9.6 vs 7.9,respectively. However, the rate of transferable embryos of lactating doner were higher than that of dried, 82.5% vs 48.1%. 2. The average number of corpus luteum and collected eggs of lactating donors under 7 years of age (6.7 vs lactating 5.3) were slightly lower than those of over 8 years of age (11.1 vs 9.2). But the rate of transferable embryoswas better in under 7 years old donors than over 8 years (81.1% vs 49.3%). were 6.0, 4.8, 1.5, 1.8 and 75%, and those in the summer were 2.9, 3.8, 2.2 and 46.7%, respectively. 3. The average number of corpus luteum was the highest in winter (10.5) and the rate of egg collection was the best in autumn (94.7%). The rate of the transferable embryo was the highest in winter (64.3%). 4. The average number of corpus luteum was the lowest (5.5) in the animals treated six or more superovulating treatments. The rate of egg collection was the best in the third treatment group (90.2%), but it was getting worse after fifth treatment, The rate of transferable embryos was the highest in the second treatment group (94.1%), and it was decreased thereafter.