Intracytoplasmic sperm injection (ICSI) is the [8][9][10].In human ICSI, high fertilization and pregnancy rates were achieved when a motile spermatozoon was injected after immobilization [6]. Dramatic advances in the treatment of severe male-factor infertility have been achieved by using ICSI, and at present, the technique of ICSI is being widely used in clinical applications for human infertility.In cattle, the first ICSI calves were born in 1990 in Japan [4]. These results showed that bovine embryos produced by ICSI with a dead (killed) bull spermatozoon could develop into live calves. The normality of the calves (growth, behavior and reproduction) was also reported after five years [11]. However, the cleavage rate of oocytes after ICSI was very low (12 percent, 61/ 507) [4], the production rate of transferable embryos was low for practical use [4,[12][13][14][15][16][17][18][19][20][21][22][23][24]. In other domestic animals (pig, horse and sheep), the cleavage rate of ICSI oocytes was also low [20,[24][25][26][27][28][29][30][31][32].There are many excellent reviews on the current status and future of ICSI in humans [33], mice [34] and domestic animals including cattle [35][36][37][38][39][40], and this pa--Reviewper reviews the problems with and improvements to ICSI for practical use in domestic animals, especially in cattle.