Non-communicating syringomyelia (NCS) can be associated with different disease processes such as arachnoidytis, trauma or tumor. Approximately 12 cases, documented radiographically, of the association of non-communicating syringomyelia and multiple sclerosis (MS) have been described but their relationship remains obscure. In 3 patients with laboratory supported MS spinal magnetic resonance imaging (MRI) revealed a central cystic cavity. In 2 patients lesions on the spinal cord above the cavity were demonstrated. At 3-year follow-up in 1 patient, no change in the cavity was detected. Although 3 cases are insufficient for providing a definitive conclusion on the relationship between these two diseases, we suggest that demyelinating lesions have to be regarded as possible causes of spinal, asymptomatic cavities.