A genetic factor contributing to multiple sclerosis (MS) disease risk is evident by the increased prevalence of disease among siblings of probands. A recent genome screen on Canadian sib pairs suffering from MS identified linkage between the genetic marker D6S461 and MS, and showed disequilibrium in transmission of its 260-bp allele from heterozygous parents to affected siblings (Ebers et al., 1996). The present study examined the allelic segregation of this marker among MS patients of Iraqi Jewish and Ashkenazi origin, two homogeneous ethnic groups that differ considerably from Caucasians. The frequency of the 260-bp allele reached 28.3% among Iraqi MS patients (n = 30) and 25.2% among the Ashkenazi patients (n = 121) compared with 19.6% (n = 28) and 21.3% (n = 115) in respective origin-matched controls (for the combined data set, p = 0.18). A secondary analysis of the frequency of the 260-bp allele in clinical subgroups showed a frequency of 38.1% among patients with juvenile MS (i.e., onset by 21 yr of age) of Ashkenazi origin (n = 21, p = 0.019) and 38.8% in the combined pool (n = 27, p = 0.0045). Most (90%) of the juvenile MS patients belonged to the relapsing-remitting subgroup, which itself showed a frequency of 28.5% of the 260-bp allele (n = 121, p = 0.045). The results suggest that the D6S461 region may contain a locus contributing to an early onset of relapsing-remitting MS.