Fever is a common complaint of childhood, and can be defined as an oral temperature higher than37.5 °C or a rectal temperature higher than 38 °C. It occurs in response to infection or trauma and should be differentiated from hyperthermia. Diagnosis of fever is different according to the age group of children. It can be difficult under three months of age, because of immature thermoregulatory responses and these infants are at greater risk of serious infections than are children over three months of age with the same temperature. In the evaluation of fever a careful history and physical examination and appropriate laboratory studies such as a complete blood count, urine analysis, and a lumbar puncture may be necessary. Acetaminophen is the first choice as an antipyretic drug in the treatment. An overall evaluation and prompt diagnosis of the underlying illness will decrease morbidity and mortality