In this article, a non-destructive method using 3D X-ray imaging to find dielectric breakdowndefects in multilayer ceramic capacitors (MLCCs) aged by high temperature and high voltage in an accelerated test is presented. In total, 64 aged samples were investigated using 2D X-ray imaging and half of them were further analysed with 3D X-ray imaging. Miniscule dielectric breakdown defects located in the MLCC active region are extremely difficult to identify solely using cross-section analysis or 2D X-ray imaging. In this study, the information provided by the 3D X-ray analysis was used to localize the defects for cross-section analysis. Cross-section analysis was performed to verify the dielectric breakdowns and their locations. 3D X-ray imaging is an effective method for detecting dielectric breakdown defects in MLCCs due to its short analysis time and high accuracy. This further facilitates failure analysis processes by providing the required grinding depth in cross-section analysis procedures.