The exact pathophysiological mechanisms leading to chronic rhinosinusitis (CRS) still to a large extent remain obscure. However, recently there has been some progress in elucidating the etiology of nasal polyposis, especially regarding tissue eosinophilia as well as the role of aspirin intolerance and eicosanoid mediators. Endonasal sinus surgery has evolved to be the treatment of choice in CRS and nasal polyposis in all cases where conservative treatment has failed or resulted in only a partial or temporary relief. Today, state of the art in surgical technique includes the ability to combine microscopic and endoscopic procedures. Regardless of technical advances like powered instrumentation or computer-aided surgery, in a modern protocol, surgical therapy can offer only one option within a complex and individually tailored therapeutical concept. This review discusses current concepts and new developments in the diagnosis and treatment of CRS and nasal polyposis.