What is the human macrobiome? What are the factors affecting its diversity? How is it related to the immune system? Does it play a protective role or can it cause infections? What is its role in inflammatory urinary diseases and cancer? Is there a role for probiotics, prebiotics and euviotics? Let us get better acquainted with the unknown world of microbes that reside in our body and are linked to many urological diseases whose aetiology still remains unknown.