The control of bovine male reproduction is a finely orchestrated system. However, the mechanism has already been predetermined by the bull's genetic makeup and, to a lesser extent, the environment. Although the endocrine system appears robust, excessive pressures can inhibit or arrest the process. Similarly, structural limits to the bull's anatomy exist, and exceeding them can result in permanent damage. Hence, a thorough understanding of the anatomy and physiology allows successful management of the breeding bull.