This paper describes a simple, fast and sensitive liquid chromatography-mass spectrometry method for quantification of an anti-thrombocythemic agent, anagrelide in human plasma. The samples were subjected to a liquid-liquid extraction after addition of a buffer and an internal standard. Chromatography was performed on an Inertsil ODS2 column and the extract was injected onto a HPLC system coupled with mass spectrometric detection. Linear responses for standards were observed from 50 to 7500 pg/ml. The accuracy of intra-assay and inter-assay were in the ranges 4.3-4.4% and 4.8-5.6%, respectively. The method is simple and reproducible with a run time of less than 2 min.