Dialysis patient inevitably suffered from uremic bleeding although improvement of dialysis care in the past decades. Physicians used to check bleeding time as a surrogate marker for uremic bleeding. However, bleeding time isn't accurate and as well known, is poorly correlated with clinical bleeding such as surgical bleeding. Platelet function assay (PFA) is a newly developed method to measure platelet aggregation in vitro and is validated in many sorts of platelet disorders. Recently, PFA was also used to evaluate aspirin responsiveness in patients who had taken aspirin. Our study is aim to investigate uremic thrombocytopathy via PFA of dialysis patient in Taiwan. Furthermore, we will study aspirin resistance in dialysis patient.