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The microstructures of bulk Zr(2)Al(3)C(4) and Zr(3)Al(3)C(5) ceramics have been investigated using transmission electron microscopy and scanning transmission electron microscopy. These two carbides were determined to have a point group 6/mmm and a space group P6(3)/mmc using selected-area electron diffraction and convergent beam electron diffraction. The atomic-scale microstructures of Zr(2)Al(3)C(4) and Zr(3)Al(3)C(5) were investigated through high-resolution imaging and Z-contrast imaging. Furthermore, intergrowth between Zr(2)Al(3)C(4) and Zr(3)Al(3)C(5) was identified. Stacking faults in Zr(3)Al(3)C(5) were found to result from the insertion of an additional Zr-C layer. Cubic ZrC was occasionally identified to be incorporated in elongated Zr3Al3C5 grains. In addition, Al may induce a twinned ZrC structure and lead to the formation of ternary zirconium aluminum carbides. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.