11 Leghorn, New Hampshire and New Hampshire X Legnorn cocks, aged 15 months, as well as 23 White Leghorn hens were used in the examination of deep freezing preservation of fowl spermatozoa. The semen was processed and frozen by Lake's method modified by Lada-Gorzowska et al. (1975). These procedures included three principal points:
(1) The temperature of semen samples was gradually reduced to －20°C before the deep freezing in liquid nitrogen (－196°C).
(2) Before insemination, the glycerol was removed from the semen by centrifuging a 700 gl at 5°C and a non-glycerol diluent by Lake was added.
(3) Artificial insemination was intra-vaginal (about 4 cm depth), estimated to be in the vicinity of the sperm-host glands.
The average percentage of fertile eggs following single inseminations in three trials was 56.7 percent, ranging from 53.1 to 63.6 percent.