Data on the GM and KM haplotypes and RFLPs in the immunoglobulin IGHG loci are reported intending to evaluate the genetic contribution of the different populations (Europeans and Africans) who settled Tenerife Island. The GM and KM allotypic systems reveal an estimated European genetic admixture of 88%. The only possible African contribution is the presence of the GM*1,17;..;5* haplotype (2.5%), but no other traces of Black African characteristic haplotypes are found. Although new RFLP haplotypes are described, DNA variation is similar to that reported in Caucasoids with a marked absence of restriction fragments characteristic of Black Africans.