Atherosclerosis is a self-sustaining inflammatory fibroproliferative disease that progresses in discrete stages and involves a number of cell types and effector molecules. The potential importance of the coagulation, anticoagulation, and fibrinolytic systems in atherosclerosis is based on the observation that fibrin deposits and fibrin degradation products are resident in atherosclerotic plaques. A number of investigations have been conducted to probe the relationships between components of the hemostasis system and atherosclerosis; and these types of studies proliferated after the availability of mice genetically manipulated to emphasize the impact of genes of interest. In order to summarize recent progress in this area, this review is focused on mice lacking individual hemostasis genes and their contributions to steps of the atherosclerotic process.