The invention relates to a dispensing unit for dispensing two fluid substances. The dispensing unit comprises a pump assembly (2) having a first (4) and a second pump (5) which can be actuated by common, manually operable operating means (6) in order to simultaneously dispense the two fluid substances. The dispensing unit also comprises a reservoir assembly (3), the reservoir assembly comprising two reservoirs which are each provided at an outlet side with an outlet and are each delimited by a movable piston (13, 16) on the other side from the outlet, which pistons, during the dispensing of the fluid substances, move toward the respective outlets. According to a first aspect of the invention, the reservoir assembly (3) and the pump assembly (2) are separate assemblies which can be coupled to one another, in such a manner that in the uncoupled state each reservoir can be filled through the outlet of the reservoir, after which the pump assembly and the reservoir assembly are coupled to one another.