BACKGROUND AND OBJECTIVE: From the viewpoint of traditional medicine, tongue reflects internal body states. The purpose of this study is to summarize the viewpoints of Persian Medicine (PM) references regarding importance of diagnostic uses of tongue.

METHODS: Authentic PM manuscripts and perspectives of their writers were investigated in this descriptive study. We also searched online scientific databases such as PubMed, Scopus, Google Scholar, Magiran and SID for keywords such as "Tongue" and "Traditional Persian Medicine" and their Persian equivalent.

Results: In our initial survey, we obtained 208 articles that were somehow related to significance of tongue in traditional medicine; among them, 66 articles were related to diagnostic indices of tongue in Traditional Chinese medicine (TCM). No research was found to be independently dedicated to status of tongue in PM. From the viewpoint of PM manuscripts, features such as color, size, form, heaviness, dryness and wetness of tongue play a key role in diagnosing the condition of internal organs, particularly stomach, brain and liver.    

CONCLUSION: According to the results of this study, although PM references emphasize on using features of tongue as diagnostic criteria, no specific pattern or category has been presented regarding diagnostic criteria of tongue so far. Therefore, designing standard tools for determining tongue features is essential in PM researches