The study was designed to determine whether there is an association between the comorbidity as atopy, bronchial asthma, aspirin intolerance and eosinophil infiltration of the upper airways, severity of the sinonasal disease and rate of revision sinus surgery in patients with nasal polyps. One hundred and fifty patients were enrolled in the prospective study. Differences in CT score, rate of revision surgery, concentration of eotaxin and eosinophil cationic protein in nasal lavage fluid (NALF) and distribution of eosinophils in NALF and nasal tissue in patients with chronic rhinosinusitis with nasal polyps (CRSwNP), chronic rhinosinusitis without nasal polyps (CRSsNP) and control group were investigated. We focused on the relationship between presence of comorbidity (atopy, bronchial asthma and aspirin intolerance) and severity of the disease, the need of revision surgery and markers of eosinophil inflammation in upper airways in patients with CRSwNP. Patients with CRSwNP had more severe form of the sinonasal disease, higher rate of revision FESS and significant higher presence of markers of eosinophil inflammation in NALF and nasal tissue than patients with CRSsNP (P<0.05). Atopic and non-atopic asthma as wellas aspirin sensitivity significantly more often coexisted with CRSwNP. Comorbidity did not influence eosinophil infiltration or severity of the disease in patients with CRSwNP. Presence of comorbidity (atopy, bronchial asthma and aspirin intolerance) has no impact on severity of the disease or eosinophil content in the upper airways in patients with CRSwNP.