Epitaxial lithium tantalate (LiTaO3) thin films were grown on the hexagonal plane of sapphire substrates by metal organic chemical vapor deposition. Two crystallographic variants, related to each other by 180° rotation around the c axis, as well as non-180° domains were determined by transmission electron microscopy from cross-sectional samples of these films. A structural model for the non-180° domain is proposed and the possible formation mechanisms are discussed.