1. Objectives To examine appearances is essential of diagnosing Sasang constitution. It has been studied in various way, we focus the correlation between morphology of mouth and digestion. 2. Methods We have collected 231 cases of participants who were diagnosed sasnag constitution and measured morphology of mouth and analyzed the correlation between morphology of mouth and digestion. 3. Results and conclusions In result of analyzing the relation between morphology of mouth and digestion, morphology of mouth have correlation with digestion. And also morphology of mouth have correlation with digestion according to sex and sasang constitution.