Various orientations of grains in polycrystalline films prepared on (001) substrates by the d.c. sputtering method were studied by x-ray diffraction experiments. The relation between the a and b axes of the thin film and the in-plane lattice vectors of the substrate has been directly obtained by an x-ray reflection scan. The orientational relations agree well with the predication of a simplified theory of a near-coincidence site lattice between and . The grains were found to have a high probability of forming low-angle or low- boundaries among themselves. These grain boundaries are of low energy, free from extraneous phases, and exhibit a high connectivity of Mn - O - Mn nets. Therefore, the boundaries can still support the GMR effect.