Acoustic microscopy offers materials scientists not only high resolution, but also the ability to image sub-surface and surface features by its unique elastic contrast mechanisms. It is a particularly powerful tool for detecting discontinuities such as voids and cracks, and for characterizing interfacial boundaries between different phases. This paper describes the application of acoustic microscopy to two important classes of low-ductility material: engineering ceramics and ceramic-fibre composites. Images of a wide range of near-surface defects are presented for the six ceramics studied, including porosity and microcracks. An application to crack length determination during indentation tests is also discussed. In the composites, there were systematic variations in contrast from the fibre-matrix interface, which appeared to correlate with changes in interfacial strength. Finally, the line-focus microscope was used to demonstrate how the Rayleigh velocity and attenuation can be used to characterize the microstructure of ceramics and ceramic composites.