A wiper blade for the cleaning of windows of motor vehicles, the wiper blade having: - at least one spray channel (103, 104), arranged on the wiper blade, with spray openings for the discharging of washing fluid onto the window, - at least a first connection (16; 16a; 16b) for connecting the spray channel (103, 104) to an external hose line for the supply of the washing fluid, - at least one adapter (10; 10a; 10b) for connecting the wiper blade to a wiper arm (2; 2a) of a wiper device, wherein the adapter (10; 10a; 10b) having two first and second connections (16; 16a; 16b, 22; 22a; 22b) which are separated from each other hydraulically, the first connection (16; 16a; 16b) is arranged on the adapter (10; 10a; 10b), and the adapter (10; 10a; 10b) is arranged hydraulically in operative connection with a second connection (22; 22a; 22b), likewise arranged on the adapter (10; 10a; 10b), which is connected with the spray channel (103, 104), the second connections (22; 22a; 22b) which are connected with the spray channels (103, 104) are respectively constructed as through bores (23; 23b), arranged parallel to each other, with respectively two connecting pieces (25; 25a) for the spray channels (103, 104), the adapter (10; 10a; 10b) is constructed as a single-piece plastic injection moulded part, the adapter (10; 10a; 10b) has in a fastening region which serves for fastening the adapter on the wiper arm two holding brackets (13; 13a, 14; 14a) arranged parallel to each other on the longitudinal sides of the adapter (10; 10a; 10b) characterized in that the two holding brackets (13, 14) have respectively a transverse bore, which serves to receive a transverse bolt, which in turn is surrounded in the region between the two holding brackets (13, 14) by a sleeve arranged so as to be rotatably movable to the transverse bolt. - at least one spray channel (103, 104), arranged on the wiper blade, with spray openings for the discharging of washing fluid onto the window, - at least a first connection (16; 16a; 16b) for connecting the spray channel (103, 104) to an external hose line for the supply of the washing fluid, - at least one adapter (10; 10a; 10b) for connecting the wiper blade to a wiper arm (2; 2a) of a wiper device, wherein the adapter (10; 10a; 10b) having two first and second connections (16; 16a; 16b, 22; 22a; 22b) which are separated from each other hydraulically, the first connection (16; 16a; 16b) is arranged on the adapter (10; 10a; 10b), and the adapter (10; 10a; 10b) is arranged hydraulically in operative connection with a second connection (22; 22a; 22b), likewise arranged on the adapter (10; 10a; 10b), which is connected with the spray channel (103, 104), the second connections (22; 22a; 22b) which are connected with the spray channels (103, 104) are respectively constructed as through bores (23; 23b), arranged parallel to each other, with respectively two connecting pieces (25; 25a) for the spray channels (103, 104), the adapter (10; 10a; 10b) is constructed as a single-piece plastic injection moulded part, the adapter (10; 10a; 10b) has in a fastening region which serves for fastening the adapter on the wiper arm two holding brackets (13; 13a, 14; 14a) arranged parallel to each other on the longitudinal sides of the adapter (10; 10a; 10b) characterized in that the two holding brackets (13, 14) have respectively a transverse bore, which serves to receive a transverse bolt, which in turn is surrounded in the region between the two holding brackets (13, 14) by a sleeve arranged so as to be rotatably movable to the transverse bolt.