The experiment was dealt with the pregnancy and parturition in rabbits treated with sexual hormone. The 90 Japanese white (female 83 heads, male 7 heads) each weighing frown 3.0∼3.5㎏ and P.M.S., estrogen and progesterone were used in this stury. fihe method of treatment anc:, results were as follows: 1. The group injected with estrogen on the first P.M.S. injecting day; All of 5 heads were unpregnanted. 2. The group insected with estrogen on the last P.M.S. injecting day; All of 5 heads were pregnanted, and litter size was 1∼8 (mean 5.8) heads. 3. The group induced estrus with estrogen before mating and injected with progesterone for 5 or 10 days; All of 5 heads were unpregnanted. 4. The group injected with progesterone for 5 or 10 days .after mating; All of 25 heads were pregnanted, but litter size showed a decrease from normal. On the term of pregnancy; The parts injected with progesterone 10㎎ for 5 or 10 days were extended for 2 days, and the other parts injected with progesterone 20㎎ for 5 or 10 days were shortened for 1∼2 days.