1. Introduction: A History of Chromium Studies 2. Basis for Dietary Recommendations for Chromium 3. Why Chromium May Not be Essential 4. Effects of Chromium(III) as a Nutritional Supplement 5. Use of Chromium as an Animal Feed Supplement 6. The Transport of Chromium(III) in the Body: Implications for Function 7. Potential and Purported Roles for Chromium in Insulin Signaling 8. Clinical Effect of Chromium Supplements on Human Health 9. Benefits of Chromium(III) Complexes in Animal and Human Health 10. Evaluation of Cr(III) Genotoxicity with cell Culture and In Vitro Assays 11. Redox Chemistry and Biological Activities of Chromium(III) Complexes 12. Overview of Cr(III) Toxicity 13. Summary: The Clinical and Nutritional Importance of Chromium