High fever is a common symptom which is considered an important problem, especially in case of undefined causes. Even though most patients generally have been treated by western medicinal treatments, Oriental medicine has developed some prescriptions having therapeutic efficacy of anti-pyrexia. The present study reports a clinical case of prolonged high fever treated by herbal drug, Dalwonum. There was no specific cause shown by blood test, urinalysis or radiologic test to explain the periodic fever over $40^{circ}C$, but body temperature slowly started normalize after administration of Dalwonum. This study informed us about the potent usefulness of Dalwonum as an anti-pyrexia herbal drug for patients having fever unresponsive to conventional therapies.