Hemophilia is a rare disorder in which your blood doesn't clot normally because it lacks sufficient blood-clotting proteins (clotting factors). If you have hemophilia, you may bleed for a longer time after an injury than you would if your blood clotted normally. Small cuts usually aren't much of a problem. The greater health concern is deep bleeding inside your body, especially in your knees, ankles and elbows. That internal bleeding can damage your organs and tissues, and may be life-threatening.