An animal identification ear tag (1) includes a male pin (2) and a female portion (5) that receives the male pin on application of the tag to an animal's ear. The tag includes a single piece moulded panel (3) which extends from a first end at the base of the male pin to a second end where the female portion is arranged. The tag may thus form a closed loop after application to an animal's ear. The female portion (5) includes an opening (6) configured to receive an end of the male pin including a locking shoulder (26), and a plurality of locking projections (11) positioned around the periphery of the opening and extending towards the centre of the opening, the locking projections being configured to cooperate with the locking shoulder to lock the male pin to the female portion after application of the tag to an animal's ear.