Although physical methods of cooling are the treatment of choice for hyperthermia, their value in the treatment of fever remains uncertain. Methods involving convection and evaporation are more effective than those involving conduction for the treatment of hyperthermia. These same methods, combined with antipyretic medication, are preferable to immersion as treatment for fever in young children but are generally not practical in adults. Febrile children treated with tepid-water sponging plus antipyretic drugs are more uncomfortable that those treated with antipyretic drugs alone, although they exhibit slightly more rapid reductions in temperature. When febrile, seriously ill patients are externally cooled and are sedated or paralyzed with drugs that suppress shivering, they may have a more rapid reduction of fever and reduced energy expenditure than if treated with antipyretic drugs alone. A risk/benefit assessment of the consequences of such treatment is not yet possible.