The apparent paradox of heightened adrenal corticosteroid levels associated with reduction in the competence of the body's defensive apparatus to cope with exposure to new microbial antigens is considered. The question is asked how this lowered defensive capability, which occurs in the face of a threat to body integrity, is consistent with Cannon's principals of the "wisdom of the body." The suggestion is offered that the immunologic response to self-antigens exposed by disease or trauma may be suppressed by corticosteroid to offset the likelihood of autoimmune attack.