A 42-year-old man presented with frequent minor nasal bleeds since 1 month. He was undergoing chemotherapy for pulmonary tuberculosis. MRI brain revealed a space occupying lesion in the right cavernous sinus extending to sphenoid sinus, with T2 inversion. An initial diagnosis of fungal granuloma was made and endoscopic trans-nasal biopsy was attempted. During surgery, a pink pulsating mass was seen in the sphenoid sinus and the procedure was abandoned. A cerebral CT-angiography done subsequently revealed a giant right cavernous segment internal carotid artery (ICA) aneurysm. He was then referred to our centre and upon admission he collapsed secondary to a major bout of epistaxis. An emergency cervical carotid artery ligation resulted in transient control of epistaxis. Owing to recurrence of bleed, trapping of the aneurysm was done resulting in cure. The present case shows that a giant cavernous ICA aneurysm can occasionally be erroneously diagnosed as fungal granuloma.