Abstract: A disinfecting assembly for connecting needles and the like to catheters is characterized by a central body comprising two parts which may be engaged together to enclose an interchangeable disinfecting element. The central body at one of its ends receives a first terminal portion which is coupled to one piece of ducting carrying a needle. The needle punctures the disinfecting element incorporated within the central body. The central body receives at its other end a second terminal corresponding to a second piece of ducting to be associated with the connection.