The charm contribution to structure functions of diffractive deep inelastic scattering is considered here within the context of the Ingelman-Schlein model. Numerical estimations of this contribution are made from parametrizations of the DESY HERA data. The influence of the, Pomeron flux factor is analyzed as well as the effect of the shape of the initial parton distribution employed in the calculations. The obtained results indicate that the charm contribution to diffractive deep inelastic processes might be large enough to be measured in the HERA experiments. [S0556-2821(99)04921-8].6011