Aim: 5,6-Dimethylxanthenone-4-acetic acid (DMXAA) is a tumor vascular disrupting agent under clinical trials as an adjacent antitumor agent.DMXAA is structurally similar to flavone-8-acetic acid (FAA), an old tumor vascular disrupting agent with anti-platelet and anti-thrombotic effects.In contrast to FAA, which causes bleeding in tumor patients, no bleeding has been reported in patients receiving DMXAA.Whether DMXAA also affects platelet function is not clear.