Interleukin (IL)-1 is a pro-inflammatory cytokine and a central mediator in the cytokine network, and is known to control important functions both in the immune system and inflammation. The activity of IL-1 is counter-regulated by its endogenous inhibitor, IL-1 receptor antagonist (IL-1Ra). IL-1 and IL-1Ra are produced and secreted by a variety of cells including those responsible for controlling immunity. A recent study indicated that IL-1 and IL-1Ra transcripts were expressed in the vessel wall, suggesting that these cytokines contribute to the development and progression of vascular diseases. In this review, we will discuss the recent advances in our understanding of the mechanism of action of IL-1 in occlusive arterial diseases such as neointimal hyperplasia and atherosclerosis, specifically in a mouse model.