PM01218 is a novel marine-derived alkaloid and has shown potent growth inhibitory activity against several human cancer cell lines. A rapid and sensitive high performance liquid chromatography/tandem mass spectrometry (HPLC-MS/MS) method was developed and validated to quantify PM01218 in mouse and rat plasma. The lower limit of quantitation (LLOQ) was 0.05 ng/mL. The calibration curve was linear from 0.05 to 100 ng/mL (R(2)>0.999). The assay was specifically based on the multiple reaction monitoring (MRM) transitions at m/z 278.4-->184.2, no endogenous material interfaced with the analysis of PM01218 and its internal standard from blank mouse and rat plasma. The mean intra- and inter-day assay accuracy remained below 15 and 8%, respectively, for all calibration standards and QC samples. The intra- and inter-day assay precision was less than 12.8 and 8.5% for all QC levels, respectively. The utility of the assay was demonstrated by pharmacokinetics studies of i.v. (bolus) PM01218 on SD rats.