A 34-year-old otherwise healthy woman had congestion and edema of the left conjunctiva for 2 months. Magnetic resonance imaging (MRI) studies shows a hypointense and irregular mass located in the region of sphenoid greater wing of the orbit, with radiologic features characteristic of a meningioma. A dural tail sign associated with adjacent muscle swelling was seen and the dural tail enhancement was greater than that of the tumour mass itself. Because eosinophilic granuloma of the orbit in an adult woman is extremely rare, the correct diagnosis was elusive at first. We report a typical dural tail sign in an adult woman with orbital eosinophilic granuloma.