Several alterations (dysbiosis) have been found in the gut microbial profile of UC patients including a decrease in diversity, Bifidobacterium and other some of commensal gut flora. Despite the impressive alterations in the gut microbiome of UC patients it is unclear whether such dysbiosis is the cause or simply the consequence of the disease state.Recent evidence shows association of disease activity and low diversity of gut flora. This is a major issue with a potential crucial impact on development of new application and on IBD management.