Directionally solidified oxide eutectic ceramics were prepared from Al2O3, Ln2O3 and ZrO2 based binary or ternary systems. Their microstructures consist of continuous networks of single-crystal Al2O3 and oxide compounds (LnAlO3, Ln3Al5O12) which interpenetrate without grain boundaries. The outstanding stability of these microstructures gives rise to a high strength and creep resistance at high temperature. Influence of growth conditions on the morphology of the as-obtained microstructures was studied. Preferred growth directions, orientation relationships between phases and single-crystal homogeneity of specimen were revealed. Low residual stresses were measured in the binary eutectics and fracture toughness at room temperature was improved by the addition of zirconia at a eutectic composition in ternary systems.