1148 of MS in UKI migrants to Australia with the prevalence in their non-migrating countrymen because prevalence rates are higher in northern England and Scotland than in the southern regions and there has been a ten-fold increase in prevalence over the last 50 years [19]. Rates for UKI, with the exception of the Orkney and Shetland Islands, were mostly in the range of 40–50/100,000 population in 1950–1965 [20–24] with more recent ones in 1970–1986 in the 60–80/100,000 range, still well above our ﬁndings in the UKI migrants [25–28]. A study of enlisted men who had served in the Army of the United States in World War II [29] had found a very strong correlation of the risk of MS with high educational level and socioeconomic status of preservice occupation: highest quartile 2.3 times the lowest. A similar correlation of higher MS risk with higher levels of education and socioeconomic status has also been found in over 2,000 Australian cases [30]. It is likely that UKI residents would be more apt to migrate if their prospects, especially after the war, were limited at home. This would result in a bias toward lower frequency MS among such immigrants than was found among their countrymen—perhaps as low as 40%; one possible explanation for their MS rates, but a confounding factor in deﬁning risk among migrants. In fact, it was only by measuring the absolute risk of MS that we were able to demonstrate the highly signiﬁcant difference between those under age 15 and those older at immigration. The present reassessment of the Australian immigration data conforms to the ﬁndings of most of the earlier studies, cited in the introduction, that migrants from high-risk to low- risk zones who are under 15 years of age at migration are signiﬁcantly less likely to develop MS than those who migrate at an older age—in contrast to our previous report [1]. 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