Many of these case studies were originally published in a small casebook Cases in Biochemistry, John Wiley & Sons, 1999. Biochemistry instructors may obtain a copy of the casebook for consideration for adoption in their courses by contacting their Wiley representative. The cases presented here are either updates of those previously published cases, or brand-new cases. Biochemistry instructors may contact me for the complete solutions to these cases. A complete set of these cases is available on WileyPLUS, the course management program available to instructors who have adopted textbooks published by John Wiley & Sons to use in their courses.