Subclinical inflammation is a candidate etiological factor in the pathogenesis of metabolic syndrome and in the progression of atherosclerosis. A central role for activated macrophages has been elucidated recently as important regulators of the inflammatory process in atherosclerosis. Macrophage differentiation and function can be modulated by a class of transcription factors termed nuclear receptors. These are activated by intermediary products of basic metabolic processes. In this review the contribution of peroxisome proliferator-activated receptors and liver X receptors to macrophage functions in inflammation and lipid metabolism will be discussed in light of their roles in macrophages during atherosclerosis. In the past decade much effort has been made to understand the mechanisms how lipids are handled by macrophages and how inflammation could promote the atherogenic process. Here, we also provide an overview of these two fields.