In this work we report on the effects of short-range correlations upon the matrix elements of neutrinoless double beta decay (0 ν β β). We focus on the calculation of the matrix elements of the neutrino-mass mode of 0 ν β β decays of 48Ca and 76Ge. The nuclear-structure components of the calculation, that is the participant nuclear wave functions, have been calculated in the shell-model scheme for 48Ca and in the proton-neutron quasiparticle random-phase approximation (pnQRPA) scheme for 76Ge. We compare the traditional approach of using the Jastrow correlation function with the more complete scheme of the unitary correlation operator method (UCOM). Our results indicate that the Jastrow method vastly exaggerates the effects of short-range correlations on the 0 ν β β nuclear matrix elements.Facultad de Ciencias Exactas