Long-term benefits of cardiovascular therapeutic interventions are often reduced due to reocclusion of the treated vessels. Therefore, a therapeutic strategy to reduce neointima formation would be of great interest. A better understanding of the mechanisms underlying apoptosis in vascular smooth muscle cells would be key in the development of such a strategy. Efficient activation of caspase-8 regulated apoptosis is largely dependent on the aggregation of FAS at the cell surface, and a method to facilitate the study of FAS clustering and its role in apoptosis in these cells would be particularly useful. Here we describe a protocol for the antibody staining of cell surface FAS foci and the application of the iCys Research Imaging Cytometer for the quantitative and morphological analysis of the cell surface FAS foci. Curr. Protoc. Cytom. 59:12.25.1-12.25.17. © 2012 by John Wiley & Sons, Inc.