Basing on the diagnostic criteria, an analysis of 687 cases of multiple sclerosis (MS) is represented according to the different forms of course, their frequency and the degree of severity. For the progressive course--either secondary after attacks or primary--a higher proportion of disease with severe disturbances resp. comparatively malignant forms have been found; furthermore, a critical time of progression could be ascertained. The determination of the disability status (using the EDSS) during a longer space of time showed a more unfavourable prognosis for the males. The development of disability was more distinct at onset of disease in the elder-aged groups. The problems of uncertain factors influencing the course and prognosis of disease are pointed out in connection with the heterogeneity of MS, basing on the pathogenetic components.