Northern Sel'kup people residing in the upper Taz and the tributaries of Turukhan Rivers were typed for immunoglobulin heavy chain (GM) allotypes. The Sel'kups exhibited a unique GM*-G haplotype circulating within the tribe in low but almost polymorphic frequency along with common GM*F B and GM*A T haplotypes, the former a Caucasian marker and the latter a northern Oriental population's marker. Contemporary Sel'kups show a higher frequency of GM*A T than the westwardly situated Forest Nentsi, reflecting recent historical events in the region such as admixture with the Evenki of Middle Siberia. Within the area located between lower Ob and Yenisey rivers, the unique GM*-N B haplotype, restricted to the Forest Nentsi, and the unique GM*-N' G haplotype, restricted to the Sel'kups, serve as GM markers discriminating between these two adjacent tribes.