The bleeding volume test is an extension of the classic Ivy Bleeding Time Test (BTT). The BTT, an in-vivo test for an abnormal bleeding tendency, involves making a small standardized cut in the skin and measuring the duration of bleeding. We hypothesize that measuring both the volume of blood lost (BV) and the BT will to provide a more useful test. The BV test is expected to provide an improved in-vivo technique for 1) investigating the effects of drugs on platelet function and 2) diagnosing diseases of abnormal platelet function such as von Willebrand disease (vWD), 3) identifying patients who are aspirin-resistant in the sense that they do not benefit from the beneficial effects of aspirin in preventing thromboembolic disease (heart attack and stroke), 4) providing insight into the effects of antithrombotic drugs such as clopidogrel, lidocaine and statins (HMG-CoA reductase inhibitors). The BV test will provide an inexpensive diagnostic test and improve patient care.