Nests of Acromyrmrex subterraneus sub terraneus were excavated in two localities of Minas Gerais to estimate their population. All the nests had flve entrance holes which were destroyed by methyl bromide application. Twenty four hours after, the fungus culture and the ants present in the Chambers were collected and weighed. In the entomology laboratory at the Federal University of Viçosa Six samples of identical weight were taken from each nest and the number of eggs, larvae, pupae and adults was counted. Total weight of the nests ranged from 1,30og to 2,684 g. Egg percentage varied from 62% to 21.1%; larvae averaged between 0.6 to 5.4 % and pupae from 70% to 843% %. The total number of individuals varied from 10,248 to 20,872. In general, the number of minor workers that are involved in fungal and brood care was about 9,4 times lower than the number of foragers. A positive significant correlation ( r=0.896) was found between the number of pupae and that of adults.