That would depend on the source of the bleeding. If you have some type of sore or pimple on the skin of your breast, you should evaluate it the same way you would if it were on the skin of your belly or arm. If your nipples are bleeding, they might be irritated by your bra or showing an allergic reaction to an ingredient in your soap or body lotions. If the blood is coming from inside your breast and leaking out of your nipple, you have a condition called "nipple discharge." This link will take you to an article that will explain some of the causes of nipple discharge and when to see a doctor about it.