Thin films of Pb(MgxNb1−x)Oz were produced by reactive sputtering from a lead target and columbite magnesium niobate powder targets at temperatures of 500–700°C on Pt/Ti/Si, Pt/SiO2/Si, MgO(lOO) and SrTiO3(100) substrates. The films in general deposited on Pt consisted of PbO and pyrochlore phases depending upon the deposition temperature. ICP analysis revealed that the films contained slightly less Mg than the target. This was attributed to negative ion preferential resputtering of the film within the discharge. However, films deposited at 650°C on MgO and SrTiO3 substrates from a lead target and magnesium niobate target which contained excess MgO, contained a highly oriented perovskite (100) Pb(Mg1/3Nb2/3)O3 [PMN] phase according to X-ray diffraction analysis. It was observed that the substrate composition and orientation greatly influenced the crystallinity of the deposited films.