 Metallic biomaterials used in medical devices in humans are primarily chosen for their corrosion resistance, which affects functionality and durability, and is a key factor determining biocompatibility. The body environment presents challenges with respect to corrosion control, and this invited review paper analyzes the effects of corrosion on biocompatibility, discusses the kinetics of corrosion, passivity, breakdown, and regeneration in vivo, reviews commonly used metallic biomaterials and their corrosion performance, highlights principles of implant failure, retrieval, and failure analysis, describes common corrosion processes in vivo, and outlines approaches to control corrosion. This article was authored by Nomellius.