Single‐crystal films of perovskitelike (La,Ca)MnO3with very smooth surface were grown epitaxially on (110) NdGaO3substrates by a simple facing‐target sputtering technique. Their in‐plane and out‐of‐plane crystal structures were examined by means of a novel double‐crystal x‐ray diffraction technique. Thecaxis of the samples lay in the film plane. All rocking curves were found to have a full width at half‐maximum of about 0.01° which is smaller than all reported structure data for ceramic thin films. ©1995 American Institute of Physics.