We investigated the influence of zinc and its binding proteins on the immune system in 21 elderly and 20 young subjects. We detected a deficiency of zinc in the serum of the elderly. Albumin levels were within physiological range, but α 2 -macroglobulin was significantly increased in the serum of elderly subjects. Using a whole blood assay, we found decreased production of interferon-γ (IFN-γ) and soluble interleukin-2 receptors (SIL-2R) in the elderly, whereas interleukin-10 (IL-10) production was greater than in the young controls. To exclude cellular defects, we measured lymphocyte subpopulations. In elderly subjects, we detected lower quantities of CD8 + , CD8 + /CD45RA + and CD4 + /CD45RO + cells, but not CD4 + cells, than in young subjects. Other lymphocyte subpopulations were comparable for both groups. These findings suggest a dysregulation between TH 1 cells and TH 2 cells in the elderly, which may be a result of long-term zinc deficiency. Zinc reconstitution showed no beneficial effects as measured by T cell activity.