The hyperarid Atacama Desert, without vegetation, extends for 740 km N to S in Chile. The presence of vertebrates with low mobility in this environment indicates the development of special adaptive capacities and the presence of little-explored ecosystem interrelations. We studied the distribution and density of reptiles and mammals in two altitude gradients of 76 km each. On the other hand, we use a stable isotopes analysis for characterization of the trophic niche in reptiles. We found that the reptiles and mammals are infrequent and have low densities. The silverfish of the Zygentoma order are key prey in this community. Reptiles overlap in the consumption of trophic sources, but differ in their positions in the trophic web. The information is complemented with information about predation among reptiles in this extreme ecosystem.