The chaperonin of the extremely thermophilic archaeon Sulfolobus solfataricus has been imaged for the first time under native conditions using the atomic force microscope. This technique allows to visualize the structure of biomolecules in solution under physiological conditions providing a nanometer resolution topographic image of the sample. Single molecule studies can reveal fine structural details, providing a powerful insight into the active conformation of a macromolecule, and also allowing to detect different conformational states corresponding to functional changes.