Churg-Strauss syndrome (CSS) is a systemic necrotizing vasculitis of the small and medium vessels, associated with extravascular eosinophilic granulomas, peripheral eosinophilia and asthma. This is a rare syndrome of unknown etiology, affecting both genders and all age groups. CSS patients usually respond well to steroid treatment, although relapses are common after it ends. Timely diagnosis and treatment generally lead to a good prognosis with a 90% survival rate at one year. A brief review of CSS is presented, with particular attention to diagnosis, therapy and recent developments in this area. The authors then report and discuss the clinical, laboratory and imaging characteristics of four patients admitted to an Internal Medicine Department with this diagnosis. The treatment, response and follow-up of the cases are also described.