Аннотация:The potentialities of a new method--magnetic resonance tomography (MRT)--as applied to the diagnosis of paranasal sinusitis are discussed. The method permits detection of inflammation in the paranasal sinuses identified as a significant enhancement of a signal in the projection of the affected sinus. This paper presents two cases: patients with rhinosinusogenic cerebral arachnoiditis and arachnoencephalitis in whom paranasal pathologies which had no clinical manifestations were diagnosed by MRT. This helped to choose adequate therapy. In contrast to X-ray methods, MRT causes no unnecessary irradiation which allows repeated examinations.