Metallic materials have been used as biomedical implants for various parts of the human body for many decades. The physiological environment (body fluid) is considered to be extremely corrosive to metallic surfaces; and corrosion is one of the major problems to the widespread use of the metals in the human body since the corrosion products can cause infections, local pain, swelling, and loosening of the implants. Recently, the most common corrosion-resistant metallic biomaterials are made of stainless steels and titanium and its alloys along with cobalt chromium molybdenum alloys. It is well known that protective surface films of the alloys play a key role in corrosion of the metallic implants. Key documents on the corrosion behavior of the metallic biomaterials in human body have been compiled under this chapter as a review.