Wegener's granulomatosis(WG) is an uncommon inflammatory which rarely is reported to cause Horner's syndrome. We report a case of HS in a patient with WG caused by pulmonary involvement. A 47 year-old man presented with cough, fever, and chest pain. On exam, he was noted to have ptosis and miosis on the left eye. ChestX-ray and thorax computed tomographic scan of the chest revealed a cavitary lesion in the apicopos- terior segment of the left upper lobe. HS caused by pulmonary manifestation ofWG is rare and such a disease process needs to be considered in the differential diagnosis.