Female hemophilia carriers have not usually been considered at increased risk of bleeding unless factor levels are below 40%. In this observational study of comparing female carriers and non-carriers, carriers showed an increased risk of bleeding, particularly after medical interventions. The risk appeared to increase with levels below 60%. Clinicians should be aware that female carriers of hemophilia may be at increased risk of bleeding. Future research is needed to confirm the bleeding risk, identify factor levels predisposing to bleeding, and determine optimal prophylaxis/intervention strategies.