Accelerated proliferation of smooth muscle cells (SMC) is known to play an integral role in atherosclerotic lesion formation. Thus, there has been significant interest in defining both positive and negative regulators of SMC growth. We have applied a novel optical technique referred to as four-dimensional light scattering fingerprinting (4D-ELF) that enables non-invasive assessment of living cells. 4D-ELF can serve for highly sensitive detection of slight alterations in cellular and subcellular microstructure. Using 4D-ELF, we characterized the proliferation of SMC grown on two different substrates: laminin and fibronectin. Fibronectin-grown SMC have been previously shown to be more proliferative. Our results indicate that light scattering can be used to monitor the changes in the intracellular structure caused by the cell-substrate interaction and differentiate between more and less proliferative SMCs. Thus, light scattering fingerprinting may potentially provide a quick, inexpensive, and accurate means to noninvasively characterize the proliferation of living cells as well as cell-biomaterial interaction.