A needlestick prevention device for an injection device having a hollow needle comprises a sheath for attachment to the injection device. The sheath has three positions. In a first, inoperative position the sheath sealingly encloses the needle. In a second operative position a first part of the sheath is removed, a second part remains attached to the injection device and a third part is pivoted about a hinge to expose the needle. In a third, cover position the third part is pivoted about the hinge to cover at least the tip of the needle and is retained in position by a retaining device acting between the second part and the third part. The needlestick prevention device is simple to manufacture and use.