Iron and iron binding proteins are involved in various regulatory mechanisms in infections and tumors. Chronic infections and tumors are the most common reasons of anemias in hospitalized patients in industrial countries. Although a lot of investigative work has been done to identify the underlying mechanisms many details are still poorly understood. This paper gives a review of our present knowledge from experimental work, reported in the literature together with own results. The main emphasis is laid on new findings about the importance of a possible regulatory role of iron and iron bindings proteins on the surface of cells of the immune system in the immune surveillance as well as in non immune functions. Using a cytotoxic assay with a monoclonal antiplacental ferritin antibody which was developed by C. Moroz, surface ferritin was not only detected on peripheral mononuclear cells of patients with early stages of breast cancer but also in patients with rheumatoid arthritis which has not been reported so far. Possible connections of inflammatory states with tumors are discussed regarding the results with ferritin bearing lymphocytes together with other findings about the role of cell bound iron binding proteins in conditions of tumor and inflammation.