Studies on a new bacterium "Nanobacteria" cause great interest. Kajander et al. discovered this bacterium and their study on the relationship of Nanobacteria and kidney calculi introduced this topic to world's attention. "Nanobacteria" term is used to identify very tiny particles (0.2 µm) replicating autonomously and forming carbonate apatite. It is reported that nanobacteria can not be cultured in common microbiological media, but can grow in mammalian cell cultures. The bacterium can not be stained with bacteriological dyes and can not be fixed. Nanobacteria has been assigned to the α-2 subgroup of Protebacteria. Their growth can be identified with immune staining, ELISA, optic density and microscobic counting. Dulbecco's modified eagle medium (DMEM), transmission and scanning electron microscopes are being used to detect nanobacteria. The bacteria are isolated from human blood, kidney and dental pulp stones and also from animal blood and cell cultures. But there is a group of researchers criticizing these studies and refusing the existence of nanobaeria.