Abstract: A method for producing a multi-chamber syringe with a by-pass channel from a plastic material comprises the steps of producing a tubular preform from a thermoplastic material; providing a die designed to enclose the preform from the outside in an area of the by-pass channel to be formed, the at least one by-pass channel being preformed as a recess on an inner surface of the die; heating-up the preform to a temperature above the softening range of the plastic material, and positioning the preform in a predefined axial position inside the die; subjecting the preform to a differential pressure until the at least one by-pass channel is plastically formed; and cooling down the syringe body so formed to room temperature.