HAVING eliminated other known causes of middle ear bleeding such as trauma, tumors, and bleeding diathesis, investigators have called the presence of blood or altered blood in the middle ear "idiopathic hemotympanum," "idiopathic" referring to bleeding from an unknown source. The patient usually presents with the findings of a painless unilateral blue ear drum with conductive hearing loss of insidious onset. A chocolate brown sterile fluid is recovered after myringotomy. Characteristically this condition is a long standing one and difficult to treat conservatively. Similar findings may be seen in patients with middle ear effusions of sterile serous fluid. This is widely recognized today because of an increased awareness and improvement of diagnostic methods as well as, probably, an increased incidence resulting from the after effects of antibiotic therapy for middle ear infections. Occasionally the ear drum in chronic serous otitis media will appear bluish, but not as intensely blue-black in