NDT techniques are being pushed to detect smaller and smaller defects in materials and high-tech products that are fabricated using nanotechnologies. The term “nano-NDE” describes the application of NDT techniques with a spatial resolution of 100 nm or better to detect early imperfections and to locate small-scale flaws in materials and components. To evaluate the consequences of sub-μm defects to reliability and lifetime of a product, local materials parameters have to be determined quantitatively. For these tasks, characterization techniques must be developed further or newly established. Since semiconductor industry is a major technology driver, the first broad application of “nano-NDE” is expected in this branch. Metrology, defect inspection, and failure analysis in semiconductor manufacturing use already “nano-NDE” techniques, however, further technique and tool developments are urgently needed for the nondestructive localization of buried sub-μm defects and for fault isolation in 3D-stacked microchips manufactured using advanced packaging technologies such as wafer-level hybrid bonding. “Nano-NDE” is expected to be introduced to a much broader field of applications, particularly for the inspection of small-scale defects in high-value high-tech products and in safety-critical components. Since X-ray microscopy and nano X-ray computed tomography (nano-XCT) have the unique capability to combine sub-100 nm resolution and high object penetration, these are appropriate inspection techniques for the detection of flaws with a size of 100 nm and below in bulk materials, and therefore, they have a high potential for application in “nano-NDE.” The high-resolution imaging of micro-voids and of microcracks in microelectronic products is demonstrated.