TE‐TM mode conversion was studied in LPE‐grown garnet films with high Faraday rotation (up to 1800 °/cm at 1.15‐&mgr;m wavelength) and positive uniaxial anisotropy. High conversion ratios (80–90&percent;) were found for several modes. The phase matching is satisfactorily explained by the birefringence in the film resulting from the misfit stress.