Crystal structure and microwave dielectric properties of (1 -x)NdAlO3-xCaTiO(3) ceramics have been investigated. Crystal structure of the specimens changed with the composition. Rhombohedral structure was found for the specimens with x less than or equal to 0.1. When 0.3 less than or equal to x less than or equal to 0.7, the specimens had the tetragonal structure and it changed to the orthorhombic structure as x exceeded 0.7. Two types of the second phases were observed in (1 - x)NdAlO3-xCaTiO(3) ceramics. For the specimens with x less than or equal to 0.5, Nd4Al2O9 phase was observed and Al-rich phase was found in the specimens with x greater than or equal to 0.7. The dielectric constant (epsilon(r)) and the temperature coefficient of the resonant frequency (tau(f)) increased with the increase of x. The Q x f value of the specimen increased with x and exhibited the maximum value when x = 0.5. The microwave dielectric properties of Q x f = 45,000 GHz, epsilon(r) = 45 and tau(f) = -1.5 ppm/degreesC were obtained for 0.3NdAlO(3)-0.7CaTiO(3) ceramics.