Up to a half of the multiple sclerosis patients also suffer from depression. The risk of a suicidal behavior in these subjects is increased as compared with „non-organic“ depression. At the same time, depression further deteriorates the patients’ quality of life and his/her disability in addition to the primary neurological disorder. In the presented article, we describe a case of a thirty-yearsold woman who has suffered from multiple sclerosis for seven years, and a commorbid depression has been present for five years. The treatment with paroxetine proved unsuccessful. Passivity and resignation of the patient represent a barrier from a further therapeutic effort. In the discussion section, we consider etiology of the depicted depressive symptoms especially as for the treatment with interferon beta-1b. The literary knowledge rather testifies against a causal relationship between the administration application of an immunomodulatory agent and an occurance of a mood disorder in multiple sclerosis. We mention other therapeutic possibilities at the end of the paper.

        Key words: multiple sclerosis, depression, treatment, interferon.