Population genetic studies of Shuara Indians in Ecuador are performed for GPT, AP, PGM1, Ak, EsD, 6-PGD, Hp, Gc, C3, Bg, ChE, Tf, Pi, Bf phenotypes, IgG, IgA, IgM, C3, C3-proactivator, C4 levels and acetylator phenotypes. Some systems having a polymorphism in many other populations showed a lack of some of those alleles in the population under study (C3, ChE, Tf, AK and almost absent 6-PGD, Bg, Bf).