We evaluated 102 patients with dizziness or vertigo who were 50 years of age and over, using magnetic resonance imaging (MRI). Slow blood flow (SBF) in the vertebrobasilar system was detected in 36 patients (35%). The patients with SBF experienced dizziness or vertigo for a longer period than those without SBF. The apogeotrophic type of direction-changing nystagmus was observed in 10 of 36 patients with SBF. No significant differences were found between patients with and without SBF with other neurotological tests. Because MRI can detect both infarcts in the hind-brain and SBF in the vertebral and basilar arteries it is recommended for evaluation of vascular disorders in older patients with vestibular symptoms.