The invention relates to a retainer for mounting a tray on the infusion bar of a medical apparatus, e.g. a dialysis machine. This retainer provides the user with a tray surface for items of use on the dialysis machine. A tray to be secured on the infusion bar is necessary in particular in dialysis machines in which the screen is not integrated in the machine housing but is instead secured on the infusion bar. In such cases the surface of the machine can no longer be used as a tray surface. The retainer is easy to fit in place and remove without the aid of tools.
