Male sterility is a medical condition characterized by an inability to fertilize an ovum. In around 40% of couples struggling with infertility, male sterility is the issue. There are a number of reasons for men to be infertile, and several treatment approaches can be used to address sterility in men. Usually, treatment is provided by a fertility doctor, who can draw upon specialized training and experience to diagnose and treat male sterility.

In some cases, male sterility is caused by impotence, and addressing the impotence will resolve the issue. In other instances, the infertility may be caused by a problem with a man's reproductive system, such as decreased sperm production or poor motility among the sperm. Testing usually includes collection of the patient's history and a sperm sample, and physical examinations will be conducted as well. Environmental factors can often contribute to male sterility. Exposure to radiation and certain chemicals can cause fertility issues. The problem can also be genetic in nature. In some instances, certain courses of medical treatment can lead to sterility, in which case a doctor may recommend that a man consider having a sperm sample collected before the treatment takes place so that he has the option of having children in the future. Cancer treatment, for example, usually causes sterility, and a young man being treated for cancer may not be ready to give up the chance of having children.

Approaches to treatment can vary from correcting the underlying cause and allowing the couple to conceive naturally to collecting a sperm sample for in vitro fertilization. If the sterility cannot be addressed, a fertility doctor may recommend a pregnancy achieved with donor sperm.

Infertility can be very psychologically distressing for men, especially when it is coupled with impotence. Some men find it helpful to work with a psychologist or a similar mental health professional to discuss issues and questions which come up during the process of infertility treatment. As with infertility in women, it is important to be aware that the issue is not uncommon, and it is usually not the fault of the person experiencing fertility issues.

Some men may opt to deliberately induce sterility, either temporarily or in the long term. The vasectomy is the most well known technique used to create permanent male sterility, but it is also possible to use implants to block the passage of sperm for temporary sterility, or to utilize hormone medications to induce sterility or impotence. Male sterility is usually deliberately induced because a man does not want to have children, or is not yet ready to have children, and in some regions of the world, so-called chemical castration with hormones is used to control sex offenders.