Commercially available beryllium pebbles have been irradiated to approximately 4×1022 n/cm2 (E > 0.1 MeV) at 380°C in the EBR-II. Microstructural examination has now been performed on pebbles 3 mm in diameter manufactured by Brush Wellman, USA and contained in that experiment. This paper describes optical, scanning electron and transmission electron microscopy of these pebbles. It was found that the major effect of irradiation was formation of small, highly non-equiaxed bubbles. The bubbles were thin disk shapes lying on the basal plane.