Objective : This study was conducted to compare Sasang Constitutional Medicine (SCM) and Four Humor Theory (FHT). Method : 1. The theoretical comparison was focused on the central pillars of both theories, i.e., the theories of Hippocrates and his successor Galenos as well as Lee Je-ma. 2. Research papers on SCM and FHT were collected as follows. First, relevant papers were searched for using several electronic databases: Pubmed (http://www.pubmed.org.), NDSL (http://www.ndsl.kr/index.do), KISS (http://kiss.ksstudy.com), and RISS (http://www.riss4u.net.). Keywords were 'Sasang', 'constitution', 'constitutional medicine', 'humor theory', 'Hippokrates', 'Galenos', and "Dongeuisusebowon".In addition, relevant papers were searched for using the websites of The Korean Society for the History of Medicine(http://medhist.kams.or.kr), The Korean society of Oriental medical classics (http://www.wonjeon.or.kr), The Society of Sasang Constitutional Medicine (http://www.esasang.or.kr/new_home/main.htm),and The Korean Association of Oriental Medical Physiology (http://www.ksomp.or.kr). As a result, a total of 32 papers were included in the final selection. Result & Conclusion : In this study, a comparison was made between FHT and SCM in terms of physiology, pathology and therapy. We showedthat the theories share similarities as well as differences. However, in a practical sense, the two should be characterized based on their differences rather than their similarities. In conclusion, the two have something in common, but overall, they are remarkably different from each other.