The study was carried out to find out the changes of the sex hormone concentrations in the blood plasma and antrum of follicular and lutein cystic ovaries of Holstein cows. The progesterone, estradiol-17$eta$, testosterone, FSH and LH from samples of the blood plasma and antrum of cystic ovaries of cows assayed by radioimmunoassay method. The results of this study were summarized as follows : 1. The concentrations fo progesterone and estradiol-17$eta$ in the blood plasmaat estrous and luteal phase were 0.95$pm$0.18ng/ml, 11.45$pm$3.12pg/ml and 4.25$pm$0.27ng/ml, 6.27$pm$0.82pg/ml respectively. The concentrations of progesterone and estradiol-17$eta$ in the antrum fluid of follicles at estrous and luteal phase were 24.8$pm$4.12ng/ml, 54.3$pm$7.25pg/ml and 21.7$pm$3.79ng/ml, 14.3$pm$2.72pg/ml respectively, and showed significant changes among the estrous and luteal phase and blood plasma and antrum fluid of follicles. 2. The concentrations of progesterone, estradiol-17$eta$, testosterone and LH in the blood plasma of follicular cystic ovareis of cows were 0.85$pm$0.25ng/ml, 9.23$pm$2.72pg/ml, 17.12$pm$3.26pg/ml and 3.78$pm$1.02mIU/ml respectively. And the concentrations of progesterone, estradiol-17$eta$, testosterone and LH in the antrum fluid of follicular cystic ovareis of cows were 284$pm$48.21ng/ml, 389$pm$67.23ng/ml, 12.84$pm$0.29ng/ml and 1.84$pm$0.17mIU/ml respectively, and showed significant changes between in the blood plasma and antrum fluid of cystic ovaries. 3. The concentrations of progesterone, estradiol-17$eta$, testosterone and LH in the blood plasma of lutein cystic ovaries of cows were 3.40$pm$0.78ng/ml, 4.02$pm$0.42pg/ml, 10.72$pm$2.74pg/ml and 0.76$pm$0.12mIU/ml respectively. And the concentrations of progesterone, estradiol-17$eta$, testosterone and LH in the antrum fluid of lutein cystic ovareis of cows were 427$pm$35.79ng/ml, 0.76$pm$0.07ng/ml, 3.45$pm$0.57ng/ml and 0.29$pm$0.07mIU/ml respectively, and showed significant changes between the blood plasma and antrum fluid of cystic ovaries. 4. Accordingly, the diagnosis of follicular and lutein cystic ovareis of cows from progesterone, estradiol-17$eta$ and LH levels in the blood plasma and antrum of cystic ovaries of cows is thought to be possible a diagnostic means.