Haptoglobin and transferrin types were determined for 27 multiple myeloma patients and a series of case controls. No association was found between haptoglobin and the disease, which confirms the findings of an earlier investigation. However, we found a significantly increased relative risk of 2.6 for TFCICI individuals. It is suggested that the role of transferrin in erythropoiesis and cell proliferation of both malignant and normal cells, may, at least in part, explain the association. Of additional relevance may be the suggestion that TFClCI individuals have higher blood iron levels than other subtypes.