A retrospective study of clinical files of 70 pathologically confirmed cases of Multiple Sclerosis (MS) (53 women and 17 men), selected from the records of the Laboratoire de Neuropathologie Charles Foix (Hôpital de la Salpêtrière) was performed. The following data were recorded and analysed by a computer program (HP 85): sex, age of onset of disease, clinical course (classified into Remittent, Remittent-Progressive, Progressive and Acute) and the date of each new neurological symptom or sign. The mean age of onset was 36.8 +/- 12. In women, the disease began earlier (34.6 +/- 12) and the duration was longer (17.4 +/- 12). In men the age onset was 40.6 +/- 11 and the duration was 12.5 +/- 6. In remittent courses, the mean age of onset was 30.8 +/- 13 and the duration was 21 +/- 10. In progressive courses, the age at onset was 45 +/- 10 and the duration was 2. In women, progressive courses began significantly later (42.3 +/- 9.2) and were shorter (15 +/- 8) than remittent courses which began at 26.8 +/- 8.2 and lasted 23 +/- 10. The histogram of the duration of clinical courses showed three groups: acute courses (8 cases less than 5 years long), intermediate courses (41 cases, between 5 and 20 years long), and long courses (21 cases longer than 20 years). Women were more often affected with acute (7/8 cases) or long courses (20/21 cases). The mean duration of the disease was the same when the symptoms and signs at onset were motor weakness, sensory disturbances, optic neuritis or diplopia.(ABSTRACT TRUNCATED AT 250 WORDS)