Abstract: A needle of an insulin syringe with an exchangeable injection needle and with an insulin ampulla exchangeably connected to the needle is provided and has two coaxial needle portions which are arranged distant from each other. The two needle portions are separated from each other by passage stopping means. The outer needle portion, namely the injection needle, is fastened within a needle supporting body within the needle casing, and the inner needle portion, namely the connecting needle to the insulin ampulla, is arranged within a guide body which is located within the needle casing. The passage stopping means preferably is a flexible membrane or diaphragm with a self-sealing passageway, which acts in such a manner that under pressure a predetermined adjustable amount of insulin fluid is able to pass from one needle portion into the other, and that without pressure action the flexible passage of the membrane locks the flow to the outer needle portion.