Aim of the study: this review aims to deepen, in the light of current knowledge on the essential physiological functions of the gut microbiota on human health, if the so precious role of this gastrointestinal ecosystem has been identified since ancient times and what how past society supported its correct functionality. Methods: Medline - PubMed, CDC website, Scopus and WoS databases were searched to identify relevant studies on the history of gastrointestinal medicine in the past, particularly we included studies on the importance of bacterial flora on human health. Results: medical knowledge on the important benefits of the gastrointestinal bacterial flora on the whole human body dates back to very ancient times. Many evidences suggest that ancient scholars from past Asian, African and European civilizations well-understood the importance of preserving gastrointestinal ecosystem for maintaining human health, from the sophisticated drainage systems of waste water from houses and public places since today when analysing in detail functions and composition and health’s advantages of the gut microbiota’s correct functionality is making great strides. Conclusion: the close relationship existing between the gut microbiota and the host has always had a great attention in the course of history. The most recent discoveries in understanding mechanisms of gut microbiota underline its importance in preserving host health, that past civilizations cleverly understood.