Leaky wave radiation from a one- dimensional left-handed transmission line is investigated that is composed of a cut-off parallel plate waveguide loaded with dielectric resonators (DR). The left-handedness is established by the combination of negative effective permittivity due to the cut-off TE parallel plate waveguide mode and negative effective permeability originating from the macroscopic behavior of DRs under the fundamental TE resonance. The DRs are placed near an aperture on the side wall of the parallel plates. The numerical simulation and the measurement of the radiation patterns verify the backward wave propagation along the proposed waveguide, and the promising characteristics for applications to leaky wave antennas.