Granulomatosis with polyangiitis (GPA) is a necrotizing granulomatous small-vessel vasculitis that primarily affects the upper and lower respiratory tracts and kidneys. Diagnosis is typically confirmed through histopathological examination of tissue biopsies. Fiberoptic bronchoscopy (FOB) is a minimally invasive and effective diagnostic tool, especially in cases with endobronchial involvement. A 57-year-old male patient presented with rhinorrhea, intermittent epistaxis, headache, fatigue and night sweats. Despite multiple courses of antibiotics for presumed sinusitis, no significant clinical improvement was observed. Although the patient had no lower respiratory tract symptoms, chest radiography revealed bilateral parenchymal infiltrates and thoracic CT showed consolidation in bilateral upper lobes and multiple nodules in peribronchovascular areas. FOB revealed increased vascularity, erythema, edema, and inflammatory lesions in the bilateral upper lobes. Forceps biopsies confirmed a necroinflammatory process due to vasculopathy, and the presence of positive cytoplasmic (c)-ANCA autoantibodies supported the diagnosis of GPA. In conclusion, bronchoscopic examination is a valuable diagnostic procedure in patients, as it reveals endobronchial involvement and identifies appropriate biopsy sites.