Kombucha tea is a slightly sweet, slightly acidic refreshing beverage consumed worldwide, obtained by the fermentation of sugared tea by a symbiotic association of bacteria and yeasts, forming “tea fungus” []. The tea fungus broth is composed of two portions, a floating cellulosic pellicle layer and the sour liquid broth (Fig.). This refreshing beverage tasting like sparkling apple cider is often produced in the home by fermentation using a tea fungus passed from home to home. Black tea and white sugar are the best substrates for the preparation of kombucha, although green tea can also be used. Tea fungus is a best example of biofilm made by symbiotic association of acetic acid bacteria and yeasts. The association of Kombucha with human was reported to be since BC, but the exact details about the origin are unclear. Details about the invention of tea fungus are also missing in the history. Kombucha tea is prepared by inoculating the tea fungus culture into cooled sugared tea decoction along with some amount of previous batch of fermented tea and allowing fermenting in dark for 7–14 days. During fermentation, the pH reduces drastically due to production of organic acids from added sugar due to yeast and bacterial metabolism. Tea polyphenols undergo degradation or transformation by the enzymes of bacteria and yeast which was evident by changes in color of the black tea during the course of fermentation. Various enzymes have been reported to be active in kombucha tea. Tea fungus is basically cellulose network where bacteria and yeast cells are attached which finally appears as a jelly membrane. The thickness of this biofilm is due to the deposition of cellulose as layer by layer during fermentation time. Reports about the first use of tea fungus, its formation for the first time, and inventor details are missing in the history. Kombucha has been reported continuously by scientific community and users for its health benefits. Composition and the concentration of the metabolites available in kombucha after the required time of fermentation would be the sole reason for the health benefits claimed. Kombucha has a range of metabolites originated from tea plant, bacterial metabolism, yeast metabolism, sugar, and the biotransformed compounds produced during fermentation which makes it very complex to study even by the state-of-the-art instruments []. It is surprised to see in the literature that there were very less attempts taken to reveal the complex composition of kombucha tea. As an initiative to achieve this, the present chapter focussed to review the metabolites already reported in the literature.