Considerable evidence has emerged that adverse blood flow patterns are a major factor in the onset of atherosclerotic disease and may play a role in disease progression. This chapter reviews a technique, referred to as vascular computational fluid dynamics (CFD), for characterizing blood flow patterns in large arteries from magnetic resonance angiography (MRA) and velocity-encoded phase-contrast magnetic resonance (PC MR) imaging. In vascular CFD, hemodynamic conditions are modeled by the finite-element method with flow is governed by the incompressible Navier-Stokes equations. Construction of the vascular CFD models is a multi-step process. Critical aspects of the methodology are described in detail including surface reconstruction, construction of the volumetric mesh, imposition of boundary conditions and solution of the finite element model. In vitro and in vivo experimentation is discussed that demonstrates, in a preliminary manner, the validity of the methodology. Flow models are presented for carotid arteries with a wide range of atherosclerotic disease. Considerable evidence has emerged that disturbed blood flow patterns are a major factor in the onset of atherosclerotic disease and may play a role in disease progression. The proposed chapter will review a technique for characterizing blood flow patterns in large arteries from magnetic resonance angiography (MRA) and velocity-encoded phase-contrast magnetic resonance imaging. This technique, known as vascular computational fluid dynamics (CFD), has been applied extensively to the bifurcation region of the carotid artery, a common site of plaque formation. Common hemodynamic features in this region will be presented based on imaging of a series of normal subjects. Hemodynamic features in the vicinity of the carotid bifurcation will also be presented for a series of subjects with advanced atherosclerotic disease.