The microwave dielectric properties of dense ceramics of a new A(4)B(3)O(12) type cation-deficient hexagonal perovskite Sr3LaNb3O12 are reported. Single-phase powders can be obtained from the mixed-oxide route at 1320 degrees C and dense ceramics (> 96% of the theoretical X-ray density) with uniform microstructures (5-12 um) can be obtained by sintering in air at 1430 degrees C. The ceramic exhibits a moderate dielectric constant epsilon(r)similar to 36, a high quality factor Q x f similar to 45 327 GHz, and a low temperature coefficient of resonant frequency tau(f) of -9 ppm/degrees C.