The analytical method is based on liquid chromatography-mass spectrometry (LC-MS) with an electrospray ionization (ESI) interface. Serial blood samples from a 62-year-old woman who was repeatedly exposed to bromadiolone were collected, and the half-life of bromadiolone was estimated at approximately 6 days in the initial phase of elimination and approximately 10-13 days in the terminal phase. The plasma/blood ratio and the stability of bromadiolone in whole blood after storage at -20 degrees C, including thaw and freeze cycles, were also examined. The mean plasma/blood ratio of bromadiolone was 1.7, plus or minus 0.6. The stability testing found that bromadiolone concentrations decreased in whole blood samples after two cycles of freeze and thaw. The study concludes that LC-MS is a suitable method for rapid quantification of bromadiolone and other potent second-generation rodenticides (“superwarfarins”). The description of materials and methods addresses the chemicals used, preparation of the standard stock solution of bromadiolone, the equipment and procedures for the LC-MS analyses, the collection and management of the blood samples, and the calculations for bromadiolone elimination half-lives and the plasma/blood ratio of bromadiolone. 3 tables, 2 figures, and 14 references