The invention relates to an armoured ventilation grille for an opening, the grille including an outer side to be exposed to a projectile shot and an inner side to be applied to the opening, the grille including a plurality of parallel bars, the bars having a V-shaped cross-section, each limb of the V being made of of a blade, the blades being arranged in chevrons in order to form baffles such that at least one blade is located in the trajectory of the projectile shot whatever the incidence may be. The grille according to the invention wherein the outer blades is made an armoured material while the inner blades made of a ductile material, the blades all being fixed to transverse members in the bearing ranges in such a way that they can be disassembled.