F2-isoprostanes (F2-IsoP's) are reliable measures of in vivo lipid oxidation, but care is required to prevent artifactual elevation. We examined the effects of blood collection and storage on plasma F 2-IsoP's. Blood was collected into EDTA/butylated hydroxytoluene/reduced glutathione (EDTA/BHT/GSH) or EDTA, at 4 C or room temperature. Plasma was stored at -20 or -80 C for 1 or 6 months before F 2-IsoP's were assayed by GC-MS. The temperature of blood collection did not affect F2-IsoP's. However, storage at -20 C or collection into EDTA resulted in significant increases in F2-IsoP's. Blood collection into EDTA/BHT/GSH and storage at -80 C minimizes artifactual elevation of plasma F2-IsoP's. © 2014 Elsevier Inc. All rights reserved.