Filling and recirculation device of a fluid conducting system of an extracorporeal blood treatment device which has the following components: - a fluid container connector, preferably in the form of a spike, that is adapted for connecting up the single fluid connector of a medical fluid container, and - a manually operable fluid blocking mechanism which is arranged downstream of the fluid container connector and is adapted or provided in such a way so as to remain fluidically connected with the fluid container during the entire operation of the filling and recirculation device by way of the fluid container connector, characterised in that - the fluid blocking mechanism is a three-dimensional four-way valve with a first valve plane on which an inlet connector for the fluid container, an arterial line connector as well as a valve-internal coupling connector are arranged, with a second valve plane on which an outlet connector as well as a venous line connector are arranged, which is permanently fluidically connected with the valve-internal coupling connector of the first plane, and with a manually operable valve rotary piston which has a first piston control section assigned to the first valve plane and an axially spaced second piston control section assigned to the second valve plane, which are geared to each other in such a way that a. in a valve piston rotary position for flushing, the first piston control section connects the inlet connector with the arterial line connector, and the second piston control section connects the venous line section with the outlet connector, b. in a valve piston rotary position for recirculation, the first piston control section connects the valve-internal coupling connector with the arterial connector, and the second piston control section disconnects the outlet connector from the venous line connector, and c. in a valve piston rotary position for therapy, the first and the second piston control sections (142a, b) close off all connectors. - a fluid container connector, preferably in the form of a spike, that is adapted for connecting up the single fluid connector of a medical fluid container, and - a manually operable fluid blocking mechanism which is arranged downstream of the fluid container connector and is adapted or provided in such a way so as to remain fluidically connected with the fluid container during the entire operation of the filling and recirculation device by way of the fluid container connector, characterised in that - the fluid blocking mechanism is a three-dimensional four-way valve with a first valve plane on which an inlet connector for the fluid container, an arterial line connector as well as a valve-internal coupling connector are arranged, with a second valve plane on which an outlet connector as well as a venous line connector are arranged, which is permanently fluidically connected with the valve-internal coupling connector of the first plane, and with a manually operable valve rotary piston which has a first piston control section assigned to the first valve plane and an axially spaced second piston control section assigned to the second valve plane, which are geared to each other in such a way that a. in a valve piston rotary position for flushing, the first piston control section connects the inlet connector with the arterial line connector, and the second piston control section connects the venous line section with the outlet connector, b. in a valve piston rotary position for recirculation, the first piston control section connects the valve-internal coupling connector with the arterial connector, and the second piston control section disconnects the outlet connector from the venous line connector, and c. in a valve piston rotary position for therapy, the first and the second piston control sections (142a, b) close off all connectors. a. in a valve piston rotary position for flushing, the first piston control section connects the inlet connector with the arterial line connector, and the second piston control section connects the venous line section with the outlet connector, b. in a valve piston rotary position for recirculation, the first piston control section connects the valve-internal coupling connector with the arterial connector, and the second piston control section disconnects the outlet connector from the venous line connector, and c. in a valve piston rotary position for therapy, the first and the second piston control sections (142a, b) close off all connectors.