ZhenWuTang originates from Lesser Yin chapter in the ”On Cold Damage”. Lesser Yin disease is equal to the end stage of acute febrile infectious disease nowadays. The symptoms for ZhenWuTang are mostly drowsiness and fatigue. Although ZhenWuTang of Lesser Yin disease is listed as extensively used formulas with GeGenTang of TaiYang disease and XiaoChaiHuTang in Lesser Yang disease, it only focuses on Lesser Yin disease that shows end stage of life, except other miscellaneous diseases. It is therefore more important than GeGenTang and XiaoChaiHuTang. This article discusses the clinical application and a case study of ZhenWuTang.