Ten cases of otogenic and 1 case of rhinogenic brain abscess experienced during a period 1961-1966 have been reviewed. Most of the patients were in severe condition, even moribund, when first seen, but the signs and symptoms indicated a meningitis or sinus thrombosis in most cases ; the coexistant brain abscess did often not give any signs at all. Latent brain abscess manifested themselves in 2 cases after operation in general anesthesia, in 1 case after a rather small amount of intravenous infusion and in 1 case after a vertebral and cerebral angiography in general anesthesia. The masking effect of antibiotics was demonstrated in 2 cases where signs and symptoms started after discontinuation of the medication. The abscess was diagnosed and drained from the mastoid in 2 cases, in 1 of these a contralateral abscess was however found at autopsy. In 1 case a total, neurosurgical removal of the abscess was possible, and the patient is alive without symptoms 4 months after operation. In Korea there is a high incidence of cholesteatomatous otitis media in young age groups, and this, in combination with poor nutrition and lack of medical care explains the high incidence of complications. On the other hand antibiotics are for free sale without prescription and the patients often medicate themselves. When first seen symptoms and signs are often masked. Considerably increased SR, vomiting and headache seems to be the only reliable signs and symptoms of a brain abscess, and should never be neglected in the course of an otitis media or a frontal sinusitis. The spinal fluid is usually abnormal with a moderate increase of white blood cells, of which around 50 per cent are lymphocytes. The immediate cooperation with a neurosurgical service is important, but not always at hand, and in such case the otologist must not hesitate to make the mastoidectomy as the first procedure with the aim to drain the abscess if possible. General anesthesia and intravenous infusion of isotonic solutions and possibly also angiography may initiate the manifestation of a brain abscess or even cause death by increasing the intracranial pressure.