Single-crystal fibers of the layered perovskite A 2B 2O 7 (A=La, Nd, Ca, B=Ti, Nb) family were grown by the laser-heated pedestal growth technique. The dielectric constant and loss at 9 GHz were measured by a perturbation waveguide technique. The Nd 2Ti 2O 7 and Ca 2Nb 2O 7 exhibited low losses, below 0.0009. The single-crystal fiber geometry is well suited to the waveguide measurement technique and offers a rapid evaluation of the microwave dielectric properties of a range of materials.