Abstract: Vascular flows are important in physiology and implicated in many life-threatening conditions. They span various scales, from the macro- to the microcirculation, each with its own features and challenges, e.g. macrovascular flows involve complex time-dependent, fluid-structure interaction phenomena, whereas microvascular ones are governed by the multiphase nature of blood. Cardiovascular diseases remain the leading cause of death worldwide while diabetes, known to be associated with various microangiopathies, is rising at a high rate. Understanding hemodynamics across the scales, thus, is important to elucidate the onset and progression of such pathologies, aid the development of diagnostics and intervention planning and has the potential to personalise healthcare. The talk will discuss the application of in vivo, in silico, and in vitro tools to understand the hemodynamics of complex vascular pathologies such as aortic dissection and arteriovenous malformations. It will also present our efforts to understand microscale blood flows using microfluidics and in particular the effects of mechanical properties of blood such as RBC aggregation and deformability on microhemodynamics.