The domain structures and dislocations in epitaxial thin films of La0.7Ca0.3MnO3 grown on SrTiO3 substrates by pulsed laser deposition were investigated using transmission electron microscopy. It revealed that the films contained the 1/2[10 0](0) and 1/2[1 0 (1) over bar](0) types 1/2[0 1 0](0), 1/2[1 1 1](0), of antiphase partial threading dislocations, the 90 degrees- and 120 degrees-types of twin-domain boundaries, and two types 2 2 boundaries, which are often observed in bulk materials. In addition, two types of superdislocations were detected; one consisted of two 1/2[1 1 1](0) dislocations and a 1/2[1 1 1](0) antiphase boundary, and the other was composed of two 1/2[0 10]0 dislocations and a 1/2[0 10]0 antiphase boundary. These superdislocations, domain boundaries, and their relationships were extensively explored. (c) 2007 Elsevier B.V. All rights reserved.