A high-performance liquid chromatography (HPLC) positive-ion electrospray ionization tandem mass spectrometry method for the quantification of prostaglandin glyceryl esters (PG-Gs), a newly discovered class of eicosanoids, is described. All four PG-Gs (PGE(2)-G, PGD(2)-G, PGF(2alpha)-G, and 6-keto-PGF(1alpha)-G) and the prostaglandins (PGs) that are formed by their hydrolysis are simultaneously quantified. Analytes were purified via reverse-phase solid-phase extraction, separated by reverse-phase HPLC, and quantified on a triple-quadrupole mass spectrometer using selected reaction monitoring. Quantification was achieved by stable isotope dilution employing penta-deuterated (PG-Gs) or tetra-deuterated (PGs) analogs. Analyte recovery from cell culture medium was >43% for all analytes at four different concentration levels. The limit of quantification is in the range of 25fmol on-column for each analyte and the analytes exhibit a linear response over approximately a 500-fold range. This method allows simultaneous profiling of several PG-Gs and PGs without multistep sample purification or derivatization.