Metal alloys containing chromium (Cr), primarily stainless steels and CoCr alloys, are used in a wide variety of implantable medical devices. These alloys are exposed to chloride containing environments with varying oxidizing potential and complexing agents. These corrosion assisted environmental effects may result in metal ions going into solution. The toxicity of Cr is dependent on valence state. Hexavalent Cr ions are recognized to be more toxic than trivalent Cr. This paper discusses the state of knowledge regarding Cr release, the chemical and mechanical factors that most significantly affect Cr release, and the potential toxicity of Cr as it applies to longterm implantable medical devices.