Summary 1. Analyses of variance in various characteristics of semen production between bulls and between months reveal highly significant differences between bulls and between months for all factors studied except pH. 2. The average semen volume was least in July, August and September. 3. The average initial motility was least in July, August and September. 4. The average concentration of spermatozoa and total sperm per ejaculate was maximum during April, May and June. 5. The average period of sperm survival was least in August, and lower in July, September and November than during any other months. 6. The average number of abnormal spermatozoa was 25 per cent greater during July, August and September than during the next highest month of the year. 7. No significant seasonal variations in pH were observed. 8. The quality of the semen produced by the bulls in this study was significantly superior during the spring and significantly inferior during the summer. The semen produced during the fall and winter months did not vary significantly from the mean.