Progression of the eukaryotic cell through the cell cycle to induce cell proliferation is a fundamental event in developmental growth processes. Specific cell cycle proteins are critical for either inducing or suppressing the cell cycle. These proteins, therefore, have been found to be key players in regulating cell proliferation in diseases like cancer and atherosclerosis. The present manuscript reviews the process of cell proliferation in atherosclerosis and the data that have implicated the various cell cycle proteins in restenotic and atherosclerotic vascular disease.