This is a randomized controlled trial. Patients suffering from recurrent acute sinusitis episodes will be randomly allocated to two groups: intervention group, where they will receive endoscopic sinus surgery in addition to medical treatment and control group, where they will receive mere medical treatment. Both groups will be followed-up for 5 to 6 months. At baseline and after 5 to 6 months, patients will answer the life quality questionnaires SNOT-22 and RAND 36-item Health Survey. The numbers of sinusitis episodes, medical appointments for respiratory symptoms, use of medications, numbers of days lost from work or studies and numbers of days with various respiratory and adverse symptoms will be recorded with patient diaries. The potential serious adverse events (e.g. cerebrospinal fluid leak, orbital complications) related to surgery will be collected from the medical records.