Biochemistry Online is a Web-based textbook developed by Dr. Henry Jakubowski for his first-semester biochemistry students at the College of St. Benedict / St. John's University. While a few features of this Web site are specific to Dr. Jakubowski's course, the online textbook should be of use to any biochemistry student. Biochemistry Online follows a topic order and conceptual framework intended to "create a coherent and sequential understanding of biochemistry, not a fragmented one without logical connections among topics" -- a common shortcoming of traditional textbooks. Loads of diagrams and 3-D animations are incorporated into the book's nine chapters, which begin with lipid structure and end with signal transduction. Dr. Jakubowski frequently updates Biochemistry Online with the latest relevant findings published in _Nature_, _Science_, and _Chemical and Engineering News_.