Cavernous malformations can be seen anywhere in the central nervous system. However their existence in intraventricular area is very rare. Superficial siderosis is an extensive deposit of hemosiderin the leptomeninges and pial surface. Superficial siderosis due to intraventricular cavernous malformation (CM) is very rare. Here we report a 50-year-old male with superficial siderosis due to third ventricular cavernoma. The patient had multiple hemorrhages due to CM. He had subtotal surgical removal of the lesion. Lately he developed ataxia, speech disorder and right hemiparesis. Gamma knife radiosurgery was performed for the residual CM. Short period of dexamethasone treatment partly solved the clinical complaints. The present case is the first report of superficial siderosis due to third ventricular CM.