Oxidative stress induced by reactive oxygen and nitrogen species has been implicated in the pathogenesis of various disorders and diseases. Biomarkers are needed for assessment of oxidative stress status in vivo and also for health examination, diagnosis at early stage, prognosis, safe and efficient drug development, and evaluation of efficacy of drugs, foods, beverages, and supplements. Lipids are susceptible to oxidation and lipid peroxidation products are potential biomarkers for oxidative stress status in vivo and its related diseases. Recently, isoprostane, isoprostaglandin homologues from arachidonic acid, neuroprostanes from docosahexaenoic acid, hydroxyoctadecadienoic acid from linoleic acid, and oxysterols from cholesterol have received much attention as potential biomarkers for oxidative stress status in vivo. The physiological levels of these lipid peroxidation products and potential application as biomarkers will be reviewed.