In a group of 100 elderly patients with persistent depressive states, a series of investigations were carried out: hematologic, lipid, protein, energy metabolism hydroelectrolytic and acid-base balance, blood rheologic properties, immunologic, reactivity and certain humoral and regulation mechanisms. The results were compared with those obtained in two control groups, identical in number, the former in the third age without depressive states and the latter of healthy adults. The results were evaluated statistically. The results demonstrate that in depressive elderly subjects changes of the various parameters studied occur in the same direction as those in the group of elderly subjects without depression, but are far more accentuated.