Abstract: The paper presents an analysis on the pathogenesis of thirst described in Chapter on Damp-Heat. The common pathogenesis of thirst lies in damage of body fluid by heat. In the diseases due to damp-heat, thirst may also be caused by obstruction by damp-heat, exhaustion of body fluid by heat, or deficiency of yang in the middle energizer leading to disturbance in body fluid. The treatment should be given flexibly according to different pathogeneses.