The Multiscale Hemodynamics Project is a collaboration of doctors, physicists, and computational scientists working together to model human blood flow through the coronary arteries. Having effective visualizations of the simulation’s multidimensional output are vital for the quick and thorough evaluation by a cardiologist. A user study was conducted to evaluate the utility of various methods for both 3D scalar and vector representations. As a result of the study, HemoVis was developed to aid in the visualization and analysis of the endothelial shear stress (ESS) in a patient’s coronary arteries. By identifying the areas of low ESS, cardiologists are able to determine the likely sites of atherosclerotic lesion formation and can take action to prevent further progression. Acknowledgements: The research presented was supported by Harvard's Initiative in Innovative Computing and by the Cyber Infrastructure Laboratory of the Harvard School of Engineering and Applied Sciences. The CT data was provided by the Applied Imaging Science Laboratory (AISL) at Brigham & Women’s Hospital.