An accessory gearbox for a gas turbine, the gearbox including a front lateral face and a rear lateral face opposite from the front face and a peripheral rim closing the box, and at least one mounted gear train including a plurality of gearwheels meshing together, each gearwheel being carried by a central shaft held at each of its two ends by a respective rolling bearing, the rolling bearings of at least one of the two ends being fastened together on at least one perforated plate attached to the peripheral rim.