Rhinosinusitis (RS) is an inflammatory disorder of the mucous membranes of the nose and paranasal sinuses, which are almost always affected concurrently. The EPOS2012 position paper initiated by the European Rhinologic Society and the European Academy of Allergy and Clinical Immunology is a recent comprehensive source on this common disease affecting approximately 20% of the population worldwide. Inflammation, not infection, is considered the cornerstone of RS, which is considered a temporal and pathophysiologic disease continuum with various subtypes. Acute rhinosinusitis is diagnosed, if typical symptoms last less than 12 weeks. It affects approximately 10% of the European population. Acute RS is further subdivided into acute viral, acute postviral and acute bacterial RS. Acute viral RS lasts less than 10 days with decreasing symptom intensity, while acute postviral RS is characterized by longer duration or a sudden increase of symptom severity around the 5th day (\'double sickening\'). Acute bacterial RS is assumed if 3 of the following 5 criteria are additionally met: Discoloured discharge (with unilateral predominance), severe local pain (with unilateral predominance), fever (>38 masculineC), elevated ESR/CRP, and \'double-sickening\'. For the treatment of acute viral RS, nasal saline irrigations and OTC cold remedies are advised. In acute postviral RS, additional topical steroids are suggested. Advantages and disadvantages of antibiotic treatment in acute bacterial RS are detailed. Overall, the new EPOS position paper infers a reorientation in this area of high medical, pharmaceutical and economic relevance.