Nea, a red cell antigen present in 6% of Finnish people but in less than 1% of other Europeans tested, is shown to be part of the LW system. Tests on 10,025 Finnish donors show the antithetical relationship of anti-Nea (proposed name anti-LWb) and anti-LW made by LW3 people (proposed name anti-LWa). Tests on families of previously reported LW3 propositi and of LW(a-b+) Finnish donors support the hypothesis that Nea (LWb) is an allele at the LW locus which when homozygous produces the phenotype once called LW3.