This work reviews a wide range of factors that are responsible for male infertility. The normal human sperm cell measures 50-60 m in length and has head, neck, middle piece and tail. The head is oval in shape and is 3-5 m in length and 2-3 m in width. The mid-piece is slender, straight and regular in outline. It is aligned with the long axis of the head, and is approximately 7-8 m in length. Its width is about one third of the head. The tail is slender, straight and regular in outline and is 40-45 m in length. The ability to fertilize oocytes is considered as the ultimate test of sperm function. A male is said to be infertile if he is unable to impregnate his partner after one year of unprotected intercourse. Some cases of male infertility are due to anatomical abnormalities such as varicoceles. This work reviewed some natural and synthetic products that have been implicated in male infertility. There is also a section on some medicinal plants that are responsible for male infertility.