Cholesterol granuloma is a well-characterized entity comprised of a foreign-body giant cell-reaction that forms in response to the presence of cholesterol crystals. It is usually found in the middle-ear or mastoid process in patients with diseases associated with chronic inflammation such as cholesteatoma and otitis media. They are rarely seen in the mediastinum. Osseous metaplasia is an exceedingly rare feature of cholesterol granulomas only reported twice in the literature. We report a case of a cholesterol granuloma of the anterior mediastinum with osseous metaplasia in a 75 year-old man that was found incidentally during urgent coronary artery bypass graft surgery.