Abstract: An ear tag for identifying animals, enables a sample of biological tissue to be taken when the tag is applied to the animal. The tag includes a male part and a female part which are assembled by irreversible socketing. The stem of the male part includes a detachable head having a hollow distal part provided with a cutting edge for cutting out a biological sample when the head perforates the ear of the animal. The female part includes a central tube for receiving the head and at least partially receiving the stem when the ear tag is applied, the tube being associated with a detachable sample container arranged in the axial extension of the tube. The proximal end of the container has a first opening for receiving the head of the stem when the ear tag is applied, and the distal end of the container has a second opening enabling the inside of the sample container to be reached.