The continued drive to develop improved medical devices demands ever increasing levels of material performance, which in turn demands greater understanding of material nanostructure and materials interactions with the biological environment. Existing methods to determine structure and composition (e.g. SEM, TEM, EDX, SIMS, XPS, AFM) are greatly limited in their ability to provide 3-D structural and compositional information at the atomic scale. Current methods cannot readily determine true 3-D structure nor provide single atomic elemental information of especially low atomic number elements. In contrast, the recently introduced Local Electrode Atom Probe (LEAP®) microscope provides 3-D angstrom-level resolution imaging in combination with single atom compositional analysis of all elements. This presentation will discuss research to apply LEAP imaging to determine the 3-D bulk and surface nanostructure of biomedical metals and devices including 316L stainless steel specimens, a CoCrMo acetabular hip cup prosthetic, nitinol wires, and several additional materials. Unique information obtained includes nanoscale compositional uniformity, depth and distribution of implanted ions, structure and composition of surface oxides, and the nanostructure of precipitates, grain boundaries, and other internal features. Such structural information can assist in the development of improved devices and in the evaluation of manufactured devices.