The approximately three thousand Maku are distributed over a vast bi-national territory, such that it is fairly difficult to estimate the demographic parameters of the population as a whole. Due to the interfluvial nature of their habitat, which inhibited the access of pioneers, missionaries and researchers, the previous estimates, varying between 2 and 2.5 thousand, are highly precarious and far from reliable; as a result, they cannot be adequately used to estimate the populational dynamic. The studies still in progress on the demographic variables in a specific Maku group, the Hupdu, allow us to conclude provisionally that the population is stable, that is, it has neither increased nor decreased significantly in the last decades (Pozzobon, 1998). On the other hand, matrimonial exchanges with surrounding groups are numerically negligible, due to the low status of the Maku in the region's intertribal system.