Sclerosis multiplex is a disease in pathology of which a combination of inflammation, demyelinization and axonal degeneration can lead to progressive atrophy of brain and spinal cord. Without any doubt we can say that disorder of cognitive functions is also an attribute of this devastating disease with a significant influence on fundamental routine activities and the quality of life itself. Prevalence of cognitive deficit is high. 40-65 % of patients have deficit in neuropsychological tests at the beginning of the disease. The grade of cognitive deficit varies, slight cognitive dysfunction can be considered incipient phase of dementia in a patient with sclerosis multiplex. Early identification and monitoring of disorder of cognitive functions in sclerosis multiplex is a very important part of whole management of sclerosis multiplex.