Gm immunoglobulin allotypes have been studied in 1157 individuals of seven Northern Selkup populations, which account for 80% of the entire population of this west Siberian tribe. This study confirms that the northern Selkup populations are a Caucasoid-Mongoloid hybrid. Restriction fragment length polymorphism (RFLP) analysis of the IGHG genes using double BamHI-SacI digests, performed on 475 DNA samples, allowed us to describe nine new BamHI-SacI haplotypes (BS47 to BS55), eight of them being characterized by IGHG gene deletion or duplication: G1 (BS49) or G4 (BS55) deletion, G4 duplication (BS51), GP-G2-G4 multigene deletion (BS50), duplication (BS48, BS53 and BS54) or triplication (BS52). A new rare Gm haplotype 15,16*;1,17;23 has been found associated with BS52. The BS51 haplotype characterized by a duplicated G4 gene (additional 7.85 kb G4 band identifying a new G4*C5 allele) was always found associated with the Gm 5*;3;23 haplotype. A high RFLP diversity has been observed for the Northern-Mongoloid haplotype Gm 15,16*;1,17;.. which was found (1) with the BS27 haplotype characterized by a 3-exon hinge G3 gene, (2) with two different GP-G2-G4 multigene duplications, BS53 and BS54 haplotypes, which differ by the size of the duplicated G4 genes, and (3) with the BS55 haplotype characterized by a G4 deletion. In the Northern Selkups, haplotypes with duplicated genes were observed at a higher frequency (24%) than haplotypes with deleted genes (6%).