Slight, moderate but also high rises in temperature, excluding other causes of fever, can be considered symptoms of periodic syndrome originating by hypothalamic centers as soon as headache, recurrent abdominal pains, growing pains, dizziness, kinetosis. These rises aren't uncommon, but often aren't considered important and this few statistics are available. The Authors present 16 case reports of fever as periodic symptom and discuss how common factors exist in the mechanism of hyperthermia and other clinical signs of periodic syndrome (ex. migraine) but they are generally modulated differently so that disturbance of temperature regulation predominates in the first case, pain in the second.