Fever is a dynamic alteration in thermal balance caused by effects of pyrogens on the hypothalamic thermostatic set point. Thermoregulatory function remains intact during fever, but temperatures are maintained at higher levels. Shivering and vasoconstriction drive temperatures higher while causing physical exertion and distress to the patient. Biomedical research reveals potential benefits of fever, because fever-producing cytokines stimulate host defense responses. Nursing care is aimed at making rational decisions for comfort and energy conservation while maximizing the immune response. In this article the pathophysiologic process and benefits of fever are reviewed and a conceptual approach to nursing care based on knowledge of thermoregulatory responses is proposed. Nursing care measures include assessment of alterations in thermal balance, selection of appropriate measures to modify or support physiologic responses, and evaluation of outcomes of therapy. Research-based direction for care is presented, as well as gaps in scientific knowledge.