Fever is a phylogenetically ancient host reaction to invading microorganisms and other noxious stimuli. Poikylothermic organisms can reach febrile temperatures by seeking a hot environment in response to a higher set point in their thermoregulatory center. Endothermic organisms produce febrile temperatures through endogenous heat production at the expenditure of a higher metabolic rate. Nevertheless, fever has been conserved during evolution through millennia, obviously because of its advantage for host defense. Despite of these arguments most doctors, nurses and patients treat fever with antipyretics. The role of fever for the recovery from low risk infections is marginal at best. A large study of ibuprofen in patients with severe sepsis could not establish a positive or negative role on the course or final outcome of the infection in an intensive care setting. These clinical observations seemingly contradict findings in severe experimental bacterial infections in rodents but it has to be taken into consideration that these animals, in contrast to patients, received no antibiotic treatment. In patients with influenza-like illnesses non-steroidal antirhumatics (NSAR) improve fever and wellbeing with little or no evidence for undesired side-effects. It therefore appears appropriate to treat patients with these and similar infections with NSAR. Antipyretic therapy in special patient groups such as brain injury victims, patients with cardiac or respiratory failure or dementia has not been established to be indicated to overcome a worsening of these organs to fail during infections. In children with a history of fever convulsions prevention or lowering of fever does not reduce recurrence. In patients with strokes it appears advisable however to use antipyretics in case of fever despite of a present lack of a proven beneficial effect. In conclusion symptomatic antipyretic therapy should be considered for low risk infections if patient suffering from fever. For more severe infections antipyretic therapy can be applied on an individual basis without too much hope to improve outcome or cause a severe worsening of prognosis.