An extracorporeal blood treatment system has a first holder (18), a second holder (19), an infusion pump (4) and an infusion valve unit (13). The first holder (18) is mounted on a housing (1a) of the system and configured to hold a blood treatment device (2). The second holder (19) is mounted on the housing (1a) and configured to hold an extracorporeal blood circuit (3) coupled to the blood treatment device (2). The infusion valve unit (13) has a first part (13b) and a second part (13a) releasable connectable to the first part (13b). The first part (13b) is mounted on the housing (la), and has an inlet (25) coupled to the infusion pump (4). The second part (13a) has a first outlet (7a) and a second outlet (10a) that are connected to an infusion circuit configured to couple to the extracorporeal blood circuit (3). Further, the second part (13a) has a one-way valve configured to allow infusion liquid to flow from the inlet (25) towards at least one of the first and second outlets (7a, 10a), and to block fluid flow towards the inlet (25). The extracorporeal blood circuit (3) with the withdrawal and return lines (6, 5) and an air trap (8), the infusion circuit comprising the pre and post infusion lines (10, 7) and the second part (13a) of the infusion valve unit (13) form part of a disposable set which is replaced after use.
