The objective of our session at the 2008 International Bio-Fluid Symposium and Workshop was to review the state-of-the-art in image-based modeling of blood flow, and identify future directions. Here we summarize progress in the field of image-based modeling of blood flow and vessel wall dynamics from mid-2005 to early 2009. We first describe the tremendous progress made in the application of image-based modeling techniques to elucidate the role of hemodynamics in vascular pathophysiology, plan treatments for congenital and acquired diseases in individual patients, and design and evaluate endovascular devices. We then review the advances that have been made in improving the methodology for modeling blood flow and vessel wall dynamics in image-based models, and consider issues related to extracting hemodynamic parameters and verification and validation. Finally, the strengths and weaknesses of current work in image-based modeling and the opportunities and threats to the field are described. We believe that with a doubling of our efforts toward the clinical application of image-based modeling tools, the next few years could surpass the tremendous gains made in the last few.