A closed fluid transfer system for fluidly interconnecting a syringe to any one of a patient I.V. set, a vial and an I.V. bag, is provided and includes a first adapter defining a lumen and supporting a seal across a first end of its lumen, the first adapter supporting a rear end of a needle within the lumen, wherein the seal is movable relative to the needle such that a tip of the needle penetrates through the seal; and a second adapter defining a lumen and supporting a seal across a first end of its lumen; wherein when the second adapter is coupled to the first adapter, the second adapter seal abuts the first adapter seal and moves the first adapter seal relative to the tip of the needle such that the tip of the needle penetrates through the abutting first adapter seal and second adapter seal.