Introduction: Eosinophilic granulomatosis with polyangiitis (eGPA) is a rare type of vasculitis. We described the case of the patient who was admitted to our Department due to haemoptysis, in whom the model-based clinical reasoning and quick diagnostic process led to the diagnosis and referral of the patient to specialists dealing with the treatment of this disease. We wanted to emphasize the fact that the patient developed symptoms of the disease many years before diagnosis. However, these clinical problems were treated individually. A broader reflection of the patient’s symptoms may have led to earlier diagnosis and implementation of adequate treatment Objective: The aim of the study is to underline the importance of clinical reasoning on the example of eGPA model diagnostics. The combination of several clinical findings led to the correct diagnosis, which enabled the patient to obtain treatment and improved further prognosis. KEYWORDS diagnostics eosinophilic granulomatosis with polyangiitis haemoptysis anti-neutrophil cytoplasm antibody-associated vasculitis