The invention relates to a motor-pump unit having an electric motor and a pump, the pump having a suction inlet and a pressure outlet, and the electric motor comprising a motor housing which is enclosed by a cooling housing, whereby a cavity is formed, it being possible for cooling liquid to be fed to the cavity via a cooling-housing inflow and to be conducted away therefrom via a cooling-housing outflow, and the cooling-housing outflow being in flow connection with the suction inlet. In order to develop the motor-pump unit such that, if required, a flow connection can easily be made from the cooling-housing inflow to the suction inlet via the cavity and the cooling-housing outflow, it is proposed that the motor-pump unit has a connecting device which is disposed laterally alongside the pump and has a first connection, which is connected in a releasable manner to the cooling-housing inflow via a first flow channel, and a second connection, which is connected in a releasable manner to the cooling-housing outflow via a second flow channel and is connected to the suction inlet.