Abstract. -We perform Transition matrix Monte Carlo simulations to evaluate the entropy of rhombus tilings with fixed polygonal boundaries and 2D-fold rotational symmetry. We estimate the large-size limit of this entropy for D = 4 to 10. We confirm analytic predictions of N. Destainville et al., J. Stat. Phys. 120, 799 (2005) and M. Widom et al., J. Stat. Phys. 120, 837 (2005), in particular that the large size and large D limits commute, and that entropy becomes insensible to size, phason strain and boundary conditions at large D. We are able to infer finite D and finite size scalings of entropy. We also show that phason elastic constants can be estimated for any D by measuring the relevant perpendicular space fluctuations.Random tiling models [1, 2] have been intensively studied since the discovery of quasicrystals in 1984, because they are good paradigmatic models of quasicrystals. These metallic compounds exhibit exotic symmetries (e.g. icosahedral) which are classically forbidden by crystallographic rules. This is accounted for by the existence of underlying quasiperiodic or random tilings. When tiles are decorated in some manner by atoms, these tilings become excellent candidates for modeling real quasycristalline compounds [3]. As compared to perfectly quasiperiodic tilings, some specific degrees of freedom, the so-called phason flips, are activated in random tilings, giving access to a large number of microscopic configurations. The number of configurations grows exponentially with the system size in contrast to perfectly quasiperiodic tilings where it only grows polynomially. The resulting configurational entropy lowers the free energy as compared to competing crystalline phases. Despite their random character, random tilings still display the required macroscopic point symmetries in their Fourier spectra. They are as good candidates as perfectly quasiperiodic tilings for modeling quasicrystals [1,2]. The statistical mechanics of random tilings is of central interest for quasi-crystallography. But the calculation of the thermodynamical observables of interest in random tiling models has turned out to be a formidable task. Even the calculation of configurational entropy in the case of maximally random tilings where all tilings have the same energy is a notoriously difficult problem. Very few models are exactly solvable [4][5][6][7][8][9], and a large majority of calculations rely on numerical simulations. In Refs. [10,11], an original analytic mean-field theory for plane rhombus tilings with 2D-fold symmetry, in the large D limit, was proposed. Its ultimate goal is to derive valuable results on finite D tilings by estimating finite D corrections to the c EDP Sciences