Most people with a penis have two testicles in their scrotum — but some only have one. This is known as monorchism. Monorchism can be the result of several things. Some people are simply born with just one testicle, while others have one removed for medical reasons.

What are the effects of having one testicle?

There are no lasting side effects after you have one testicle removed. Having one testicle removed won't affect your ability to get an erection. For most men it won't affect their ability to have children. But for some men their remaining testicle might not work so well and this could reduce their fertility.

Can you still have kids with one testicle?

Men with one undescended testicle can still have children, but their fertility is lower than normal by roughly half. If they have surgery to correct it, especially when younger, their fertility is about the same as if they never had a problem.