A novel, normal phase liquid chromatography (LC) system with chemiluminescence (CL) detection was developed to identify and quantify phosphoglyceride hydroperoxides (PGOOH) in rat plasma. Plasma lipid extracts were separated on a 5 μm silica column (250 mm × 4.6 mm i.d.) using methanol-isopropanol (9:1, v/v). A luminol (1.5 μg ml −1 ) and cytochrome c (15 μg ml −1 ) solution prepared in 0.001 M KOH (pH 11) was used as the CL reagent solution. Retention times for the following PGOOH were obtained: phosphatidylethanol amine hydroperoxide (4–5 min), phosphatidylinositol hydroperoxide (6.5–7.5 min), phosphatidylcholine hydroperoxide (10–12 min) and phosphatidylserine hydroperoxide (18–19 min). LC peaks of the above PGOOH were calibrated against an external standard, tert -butyl hydroperoxide. The study used female Sprague-Dawley rats administered 5 mg kg −1 body weight of dimethylbenzanthracene (DMBA) maintained on a diet containing 20% lipid derived from either corn oil menhaden oil, primrose oil or fish oil concentrate. Phosphatidylinositol hydroperoxide was the only PGOOH detected. Its concentration in rat plasma paralleld the rats' tumor burden initiated by DMBA administration.