WHI-P154 [4-(3′-bromo-4′hydroxylphenyl)-amino-6,7 di-methoxyquinazoline] is a novel anti-tumor agent with unique cytotoxic activity against human glioblastoma cells (Clin. Cancer. Res. 4:1405-1414, 1998). Further development of WHI-P154 will require detailed pharmacodynamic studies in preclinical animal models. Therefore, we established a sensitive and accurate high performance liquid chromatography (HPLC)-based quantitative detection method for WHI-P154. This method allows the measurement of WHI-P154 levels in plasma, as well as in target human glioblastoma cells. Plasma and cell lysates were extracted with chloroform, dried with nitrogen gas and reconstituted in methanol : water (9:1, v/v).