Colorectal cancer is a heterogeneous disease arising from at least two precursors-the conventional adenoma (CA) and the serrated polyp. A relationship between the human gut microbiota and colorectal cancer has been shown; however, its relationship to the different early precursors of colorectal cancer is understudied. This study tested, for the first time, the relationship of the gut microbiota to specific colorectal polyp types.