Last year Antioxidants and Redox Signaling devoted a special Forum issue (Volume 7, 2005) to reviewing the current literature on isoprostanes (IsoPs) and related compounds. Awide variety of topics provided readers of that issue with important information on the chemistry and biology of these molecules. During the past year, more than 200 articles have been published in the field of IsoP research, and noteworthy advances in the area have been made. This editorial highlights selected aspects of these advances as they relate to the Forum issue. The main focus of this discussion is on the role of the IsoPs as biomarkers and mediators of oxidant stress in human disease, their mechanism of formation and metabolism, and their biologic activities.