A scanning tunneling microscope was used to record tip-sample displacements inferred from the tunnel current versus applied piezoelectric voltage. This provides a means to determine the range in which the mechanical system, especially the piezoelectric element, exhibits hysteretic behavior. Graphite and gold were used as the substrate samples. With graphite, reversible behavior of the displacements is observed until 2.1 Å; beyond this point, the system exhibits persistent irreversible behavior. In the gold system, irreversible behavior appears initially at 0.8 Å, but repeated cycling extends the range of reversibility to a displacement of 3–4.8 Å. Irreversible behavior dominates beyond this tip displacement range, although the system exhibits sporadic reversible behavior even for tip excursions as large as 46 Å. ©1997 American Institute of Physics.