We and others have found that macrophages are capable of endo- and exocytosing iron. There is pronounced iron-sequestration in macrophages of atherosclerotic lesions. The nature of the exocytosed iron and the iron-sequestration remains unclear. Many apoptotic cells have been found in atherosclerotic lesions. The mechanism of apoptosis-induction of atheroma cells is unknown. The aims of the study were to investigate (1) iron-sequestration and its relation to apoptosis in human atherosclerotic lesion by immunocytochemistry and (2) the nature of released iron from human monocyte derived macrophages (HMDMs) following erythrophagocytosis and iron-exposure.CD68 and ferritin antibodies were applied to serial sections of arterial wall segments with obvious fatty streaks using an avidin-biotin technique. The apoptosis in the artery walls was detected by TUNEL technique. HMDMs were exposed to FeCl 3 and UV-irradiated erythrocytes for different periods and then immunofluorescence was used to visualize ferritin in HMDMs with a confocal laser scan microscope.Abundant apoptotic macrophages were found in atherosclerotic lesions which also showed strong positive staining to ferritin antibodies in the same area. After erythrophagocytosis and iron-exposure a substantial amount of ferritin was detected in the HMDM supernatants with ELISA. We suggest that iron, in the form of ferritin, may be stored in lysosomes of macrophages as a consequence of erythrophagocytosis. Such iron and ferritin may contribute to cell-mediated LDL oxidation, apoptosis and foam cell-formation by becoming exocytosed in proximity to LDL within the vessel walls.