Abstract: The invention provides a miniature pump for substances such as cosmetics or pharmaceuticals. The pump comprises a cylindrical body with a bottom intake provided with an inlet valve, in which a skirt encloses a movable piston against the action of a return spring, the piston being provided with a nozzle which passes through the skirt and having an axial channel closed by an internal valve member, biased by a spring. The nozzle is provided at its top portion with an internal shoulder, its bottom portion widening out by contrast into a collar, onto which a bushing is forced by its top edge, the bushing acting externally as a piston sealing gasket, defining under the collar of the nozzle an internal chamber in which the outlet valve member is located, its base being pierced by an axial orifice which acts as an annular seat for the valve member, the return spring for the valve member and the valve member itself being introduced from below and placed inside the nozzle. This pump provides excellent spraying.