Cardiovascular disease is a major cause of mortality globally and is subject to ongoing research to improve clinical treatment. It is established that activation of platelets and coagulation are central to thrombosis, yet at different extents in the arterial and venous system. In vitro perfusion chamber technology has contributed significant knowledge on the function of platelets in the thrombotic process under shear conditions. Recent efforts to downscale this technique with a variety of microfluidic devices has opened new possibilities to study this process under precisely controlled flow conditions. Such microfluidic devices possess the capability to execute platelet function tests more quickly than current assays, while using small blood samples. Gradually becoming available to the clinic now, they may provide a new means to manage the treatment of cardiovascular diseases, although accurate validation studies still are missing. This review highlights the progress that has been made in monitoring aspects of thrombus formation using microfluidic devices.