Abstract: A novel one-piece fluid reservoir assembly for use in conjunction with an insulin infusion pump. The single piece fluid reservoir assembly includes a barrel body, a male luer fitting integral with the barrel body, a sealing surface integral with the barrel body, the sealing surface for sealing against the pump housing when the fluid reservoir assembly is inserted into the pump housing. Further, the barrel includes, as part of the one-piece fluid reservoir assembly, threads for engagement with threads on an opening in the fluid pump so that the fluid assembly can be inserted into the fluid pump, engage the threads and rotation therewith will locate the fluid reservoir assembly within the pump. Thereafter, a piston in the pump may be incrementally advanced to act upon a plunger in the barrel assembly to force a fluid within the barrel assembly through the male luer fitting and through a conduit engaged therewith to a remote infusion set.