Data from an epidemiological study are used to analyse the course of multiple sclerosis. It could be proved that the course of MS is not as haphazard as was often supposed. In general the course is described as being a chronic progressive one, in the majority of patients preceded by a relapsing-remitting period. In contrast to the relapsing-remitting phase the chronic progressive phase of the course does not show marks of being an autoimmune process. From recent data obtained by MRI and NMR spectroscopy it can be concluded that the chronic progression of handicaps in multiple sclerosis is related to neuronal and axonal damage. The relation between these different pathogenetic processes should be the aim of further research.