Relaxor-type ferroelectric ͑1−x͒Pb͑Mg 1/3 Nb 2/3 ͒O 3 -xPbTiO 3 ͑PMN-PT͒ films, 2 -3 m in thickness, with a PbTiO 3 content ͑x͒ ranging from 0 to 1 were grown on ͑100͒ c SrRuO 3 ʈ ͑100͒SrTiO 3 substrates at 650°C by metal-organic chemical vapor deposition. The effects the x value had on the crystal structure, dielectric and ferroelectric properties, and mechanical response of these films were systematically investigated. Epitaxial growth having ͑100͒ / ͑001͒ orientation irrespective of x and the constituent phase change with x were ascertained from both x-ray diffraction reciprocal space mapping analysis and Raman spectroscopy. The constituent phase changed from a rhombohedral ͑pseudocubic͒ single phase, a mixture phase of rhombohedral ͑pseudocubic͒ and tetragonal phases, and a tetragonal single phase, with increasing x. The mixed phase region was found to exist at x = 0.40-0.55, which was different from that reported for single crystals ͑x = 0.31-0.35͒. The dependencies of relative dielectric constant and remanent polarization on x showed a similar trend in the case of a PMN-PT sintered body; however, the magnitudes of these values were relatively low. The effective longitudinal piezoelectric coefficient ͑d 33,f ͒ and the transverse coefficient ͑e 31,f ͒ of 100-120 pm/ V and ϳ−11.0 C / m 2 were, respectively, calculated for a film with x = 0.39, which corresponds to a larger x edge for the rhombohedral ͑pseudocubic͒ region following the engineered domain concept proposed for PMN-PT single crystals.