{{We present the analysis of the XMM-Newton European Photon Imaging Camera (EPIC) pn spectrum of the Seyfert 2 galaxy Mrk 3. We confirm that the source is dominated by a pure Compton reflection component and an iron K alpha line, both produced as a reflection from a Compton-thick torus, likely responsible also for the large column density (1.36(-0.04)(+0.03) x 10(24) cm(-2)) which is pierced by the primary power law only at high energies. A low inclination angle and an iron underabundance of a factor similar or equal to 0.82, suggested by the amount of reflection and the depth of the iron edge, are consistent with the iron K alpha line equivalent width with respect to the Compton reflection component, which is 610(-50)(+30) eV. Moreover, the iron linewidth