This paper reviews recent progress in atom probe field ion microscopy (APFIM) and its applications to nanoscale microstructural studies of metallic materials. By employing a three-dimensional atom probe (3DAP), elemental distributions can be mapped out in a nanometric volume with a near-atomic resolution. This technique has been shown to be suitable for characterizing nanocrystalline and nanocomposite materials as well as nanometric precipitates in various commercial metallic materials. This review highlights recent APFIM and 3DAP investigations conducted in the author's group, which have contributed to our understanding of the micro structure-property relationships in novel nanocrystalline and naNocomposite alloys, as well as conventional metallic materials containing nanoscale precipitates. (C) 2002 Elsevier Science Ltd. All rights reserved.