This experiment was carried out to examine the correlation among the semen characteristics of Holstein bulls. Seventy-two samples of semen were collected from 6 Holstein bulls, 2 to 10 years old. The characteristics of the semen were estimated by ordinary methods. The results obtained in this experiment were summarized as follows: 1. Semen characteristics on an average were 6.0 ml of volume, 16${ imes}$108/ml of concentration, 92.4${ imes}$108 of total sperm number(TSN), 72.1% of motility and 4.6% of abnormality. 2. Semen volume was positively high correlated (P<0.01) with total sperm number, but negative correlation was observed with the sperm motility (P<0.05) and semen concentration. 3. In relation to their age, older bulls semen volume and total sperm number were increased (P<0.01), but semen concentration and motility were decreased (P<0.01).