Abstract: A device for the conditioning and the distribution of pasty or liquid products comprises a casing 1 in which is located a primary chamber 3 divided in two parts by a free piston 4. This primary chamber 3 communicates with a secondary chamber 7 thanks to an aspiration channel in which is located a non-return valve 9. The secondary chamber 7 comprises a piston 16 freely sliding in this chamber and tightly connected to a push button 17 which comes out of the casing. The secondary chamber communicates by an expulsion channel having a non-return valve 12 with an expulsion hole 2 of the product. Under the action of the control piston 16, the product dose contained in the secondary chamber is expelled. When the piston 16 comes back in position a new amount of product passes from the primary chamber 3 toward the secondary chamber 7, and the non-return valve 12 prevents any intake of air inside the casing.