To study the practical value of hyaluronidase preparation in the artificial insemination of the cattle, the following four experiments were carried out, and according to the results of these and those reported in the previous reports, discussion was made on the effect of hyaluronidase preparation in the artificial insemination. For the hyaluronidase preparation "Sprase" was used. ( I ) Experiments are summarized as follows. Experiment I ; Fourty-seven services were made to 35 Holstein cows. In 34 services of them, Sprase of 2,000 v. r. u. or 5,000 v. r. u, dissolved in I cc, of normal saline was put into the cervix about 20 to 30 minutes before insemination. The rest 13 services were the control and in which Sprase was not injected. No appreciable effect of the preparation on the fertility was not obtained (table 1). Experiment II ; Sixty-one of Holstein cows that had the first calving were inseminated by the semen diluted I : 3 with fresh egg yolk. Of 39 cows which did not conceived from the first service though they bad normal reproductive organs and were free from any disturbances in their genital tracts, 26 cows were inseminated by the semen diluted as above mentioned with Sprase of 5,000 v. r. u. per one cc. added. The number of services that they received were 45. The rest 13 normal cows were the control, and received 22 services (table 2). Conception was determined by rectal palpation. Fertility was about 58% in both groups respectively. These insemination records were shown in table 3. Consequently, effect of adding hyaluronidase on the fertility of bull semen was not recognized. Naturally, there was no effect on the sex of the young. Experiment III ; The semen from 3 Holstein bulls was diluted with egg yolk-glucose-citrate diluter and 5.000 v. r. u. of Sprase was added to the semen diluted seven times, 10.000 v. r. u. of Sprase to the semen diluted fifty times, and 40.000 v. r, u. of Sprase to the semen diluted seventy times respectively. In the test, the cows were inseminated by the semen treated and the total number of services was 71. In the control, cows were inseminated by semen without Sprase and the total numder of services was 123. There was no effect of hyaluronidase preparation on the fertility in this experiment either (table 4).