This paper reports recent results of our 3-dimensional atom probe (3DAP) investigations of two different examples of nanostructured materials; electrodeposited nanocrystalline Ni and NI-P alloys and melt-spun amorphous nanocrystalline Fe-Si-Cu-Nb-B-Al alloys.3DAP analysis of as-deposited nanocrystalline Ni showed a uniform distribution of about 0.1at.% of impurity atoms, most of which were sulphur. Such low impurity levels and lack of grain boundary pinning enables grain growth to occur durin...