A dispenser of fluid products includes a ring nut (2) able to be associated to a container of a fluid product and a substantially hollow dispensing head, able to slide coaxially relative to the ring nut (2); the dispensing head (8) includes a dosing chamber (14) obtained within the dispensing head (8) and a dispensing nozzle (12) to allow the outflow of the fluid product; the dosing chamber (14) has a containment volume variable between a configuration of maximum volumetric capacity when the dosing chamber (14) is isolated and a configuration of minimum volumetric capacity; the dispenser further includes a deformable membrane (15) fastened to the ring nut (2) and a deformable disc-shaped body (16) fastened to the dispensing head (8) and defining the dosing chamber (14) in combination with the membrane (15).