The first protocols book, Free Radical and Antioxidant Protocols (1) was published in late 1998. Sections were divided into three parts, covering selected biochemical techniques for measuring oxidative stress, antioxidant (AOX) activity, and combined applications. In choosing the 40 methods to be included in that book, I realized there were considerably more of equal value than that which we could have presented in a single volume. To produce a comprehensive resource, this book and a third are being compiled to expand coverage of the field. A summary of papers (2) published on this important subject emphasizes the continuing rapid growth in oxidative stress investigations relating to our understanding of biochemical reactions, their relevance to pathophysiological mechanisms, how disease may arise, and how therapeutic intervention may be achieved(3). Although there is some overlap between the categories, the ana- sis shown below illustrates where current studies are concentrated and are almost evenly distributed between free radicals and AOX. Over the last 4 yr, there has been a 55% increase in the number of papers published in the area.