The present invention concerns an attachment assembly for attaching a fluid container (7) to a fluid warmer (13) of a system for extracorporeal blood treatment, the assembly comprising: at least one hook-shaped fixture (1) located on the fluid warmer (13), at least one pin-shaped fixture (5) located on the fluid warmer (13), and at least two receiving members located on the fluid container (7) to receive the at least one one hook-shaped fixture (1) and the at least one pin shaped fixture (5) located on the fluid warmer (13). Another aspect of the invention concerns a fluid warmer (13), characterised by containing at least one hook-shaped fixture (1) located on the fluid warmer (13) and at least one pin-shaped fixture (5) located on the fluid warmer (13) of a fluid bag attachment assembly according to the present invention. Tubing guiding means (10) present on the fluid warmer (13) in conjunction with tubes of differing lengths attached to the fluid bag (7) reduce the occurrence of use error during insertion of the fluid bag (7) into the fluid warmer (13).
