The diagnostic value of magnetic resonance imaging (MRI) in patients with ophthalmoplegia plus was evaluated. Twenty patients in whom the diagnosis of opthalmoplegia plus was clinically and histochemically established underwent magnetic resonance and electrophysiological studies. Three types of neuroradiological abnormalities were found in 14 patients: (1) cerebral and/or cerebellar atrophy (n = 11), (2) hyperintense lesions of the white matter or pyramidal tract (n = 2), or (3) both (n = 1). The diagnostic yield of MRI was low, since clinically or electrophysiologically manifest lesions were missed in 4 cases and the pathological findings were non-specific, since they are seen in several demyelinating diseases. Our results suggest that MRI provides no additional information in patients with manifest ophthalmoplegia plus. We conclude that clinical presentation and evidence of ragged red fibers are the cornerstones in diagnosis of ophthalmoplegia plus.