At 1.5 μm wavelength, TE0 optical waveguide polarizers have been fabricated in LiNbO3 by proton exchange for the first time. The polarizer consists of a short proton exchanged waveguide segment between the segments of a discontinuous Ti-indiffused waveguide. The length of the polarizers is 2 mm. The measured polarization-extinction ratio and fibre-coupled insert loss of the polarizers are 42 dB and 4.3 dB, respectively.