Atomic absorptions spectrophotometric determinations of zinc in serum, granulocytes and lymphocytes after separation of blood samples of normal and alloxan diabetic rats, control persons and diabetics by the method of Böyum verify our conception that changes of metal content and structure in cells by metal chelating agents are induced primary by chemical and secondary by disturbed carbohydrate metabolism conditions. Alloxan (200 mg/kg of body weight, intraperitoneally) destroys selectively not only the B-cells of the islets of Langerhans but also the granulocytes, while the lymphocytes are not changed in respect to the zinc content and cell count. The lymphocytes of diabetics are unchanged in the zinc content, too. The earlier opinion that leucocytes belong to the slowly exchanging zinc compartments of the blood is only exact for lymphocytes, whereas the granulocytes and the serum, corresponding to an exchange pool of metal ions, may play a more important role in the transport system of the zinc.