A machine for making sanitary articles including an impermeable outer layer and an absorbent pad superposed thereon, the machine including a feed line feeding the outer web and a unit forming the absorbent pad. The forming unit includes a first feeder feeding a first web along an operating direction, a second feeder feeding a second web, a coupling station coupling the first web to the second web, a dosing/depositing station located upstream of the coupling station where a distributed quantity of absorbent material is placed on the first web. The dosing/depositing station includes an apparatus for distributing particulate material with a tank containing particulate material, a feed mechanism feeding the material and a downstream distribution mechanism receiving the material to distribute the material on a drum or conveyor. The distribution mechanism includes a diffuser and a vibrating device to shake the diffuser.
