Abstract: The author holds that Treatise on Febrile Diseases is famous chiefly for its syndrome differentiation based on the six meridians, but syndrome differentiation based on zang-fu organs is also covered in the book. Since syndrome differentiation based on the six meridians is made according to the pathological changes of the zang-fu organs and meridians, treatment is given with reference to the pathological changes of the zang-fu organs. Therefore, it is correct to say that syndrome differentiation based on zang-fu organs is also included in Treatise on Febrile Diseases.