Grain-boundary crack onset and crack volume at room temperature resulting from thermal expansion anisotropy in aluminium titanate ceramics were studied by dilatometry. Investigation revealed that specimens with low bulk density have a smaller temperature difference between sintering and crack-onset temperature than those of the specimens with high density and the same grain size. The fracture surface energy of aluminium titanate on the grain-boundary cracking in the present study was about 22 J m(-2); the grain-boundary crack volume is proportional to (grain size)(0.5).