Abstract: A precompression pump for discharging a liquid in spray form has a first inner compression chamber formed within a pump body between a valve for closing an orifice through which liquid is withdrawn from a storage container and a discharge orifice through which the withdrawn liquid is expelled to a spray-discharge head. The volume of the first chamber is variable by means of a driving piston which is continuously urged by a first helical spring towards a position corresponding to the maximum volume. A second intermediate chamber is located between the first chamber and the discharge orifice, this orifice being shut-off by a needle-valve piston which forms the precompression system. The needle-valve piston is mounted within a moving element but outside the first chamber and urged by a second helical spring to a position of closure of the discharge orifice.