AbstractTwo groups of elderly subjects who received bivalent influenza virus vaccine were identified. Those in Group I manifested marked local reactions, suggestive of delayed hypersensitivity reactions, whereas those in Group II, matched with Group I for vaccine preparation, had no cutaneous reactions. In vitro assays of immune function were performed on pairs of subjects from the two groups and included serum immunoglobulin and complement levels, antibody response to vaccine, lymphocyte transformation to mitogens (phytohemagglutinin, pokeweed mitogen and concanavalin A) and antigens (streptokinase‐strepto‐dornase, influenza virus vaccine antigens and multiple mixed lymphocytes), and polymorphonuclear leukocyte chemotactic responsiveness. There was no demonstrable correlation between delayed local cutaneous reaction and preservation of in vitro cell‐mediated immune function in these elderly indivi