The prostate is not essential for life, but it is important for reproduction. Healthy semen is the perfect consistency and environment for sperm transit and survival, and for fertilization. Semen includes enzymes like PSA (which is often measured as part of screening for prostate cancer), as well as other substances made by the seminal vesicles and prostate, such as zinc, citrate, and fructose (that actually gives sperm energy to make the journey to the egg). Semen also contains substances that may protect the urinary tract and sperm from bacteria and other pathogens.

The prostate typically grows during adolescence, under the control of the male hormone testosterone and its by product dihydrotestosterone (DHT). Testosterone is primarily made in the testes, but a smaller amount it is also made in the adrenal glands above the kidneys.

When a man is sexually aroused, the prostate pushes prostatic fluid through the ducts and into the urethra. Prostatic fluid mixes with sperm and other fluids in the urethra and is ejaculated as