Patients with primary chronic adrenal insufficiency (PCAI) in decompensation demonstrated a decrease in the total level of blood immunoglobulins, in particular IgG, with the normal level of B-lymphocytes. A decrease in IgG and an increase in IgA content was noted in the eucorticoid state; relative and absolute lymphocytosis determined by an increase in T- and B-lymphocytes was also noted. In overdosage of cortisone acetate the total number of immunoglobulins was normal, but IgA was raised and IgG lowered. The number of B-lymphocytes was significantly elevated. The number of T-lymphocytes was within normal but an increase in the level of T-suppressors was noted.