The dielectric and piezoelectric properties of polycrystalline ceramics of relaxor ferroelectric lead magnesium niobate-lead titanate modified with La2O3, (1-x) (Pb0.985La0.01)□0.005 (Mb1/3N2/3)-(x)PbTiO3, were investigated. The compositional range of 0.2 ≤ x ≤ 0.4, being near the morphotropic phase boundary, was characterized. Lanthanum doping resulted in reduction of grain size, enhanced density, a downward shift of and the dielectric maximum temperature. The final microstructures of all compositions were fine with uniform grain size distributions. Room-temperature dielectric constants Ks of 5000 and piezoelectric constants d33(s) of 500 pC/N were found for compositions near the morphotropic phase boundary (x ≈ 0.33).