SummaryBackground: Hypersensitivity to non-steroidal anti-in ammatory drugs (NSAIDs) is often associated with chronic rhinosinusitis (CRS), nasal polyps (CRSwNP) and asthma, together known as Samter´s triad. The disease is characterised by eicosanoid imbalance. In our study, we determined clinical and laboratory parameters in respect of three groups of patients: 1) CRSwNP, 2) CRSwNP and asthma (CRSwNP-A), and 3) CRSwNP with asthma and NSAID-triggered hypersensitivity (CRSwNP-AA). Our main goal was to improve the characterisation of the stages of development in Samter´s triad, pointing to the homogeneous or heterogeneous course of disease. Methodology:Forty-three patients (10 CRSwNP, 14 CRSwNP-A, 19 CRSwNP-AA) and 10 control subjects were included in the study. Nasal assessment using the CRS visual analogue score, endoscopy-and computer tomography scores, allergy tests, analysis of sinus surgeries, asthma severity and in vitro functional eicosanoid tests (FET) with peripheral blood leucocytes were performed. Results:The scores re ecting CRS symptoms such as nasal congestion, nasal discharge and smell impairment di ered between the patients groups re ecting the severity of disease (CRSwNP-AA > CRSwNP-A > CRSwNP). Eicosanoid imbalance correlated with nasal congestion, nasal discharge and loss of smell. Conclusion:The data presented support the hypothesis of the continuous development of NSAID-triggered hypersensitivity, culminating in Samter's triad.