What is hypereosinophilic syndrome? Hypereosinophilic syndrome, or HES, is a group of disorders that are characterized by elevated levels of eosinophils in the blood, called eosinophilia, as well as accumulation of eosinophils in at least one organ in association with tissue damage and dysfunction. Find our full video library only on Osmosis: http://osms.it/more. Join millions of current and fu