Multiple sclerosis (MS) is very uncommon among ethnic Asians in the Indian subcontinent, among Asians and Africans resident in the New Commonwealth countries of Africa and in the West Indies. It is also very uncommon among those who have migrated to England from those countries. In contrast, the children born in the United Kingdom of Asian, African and West Indian immigrants have, in the age groups available for study, a high prevalence of MS of a similar order to that occurring in the general population of England.