In spite of the wide use of animals for military purposes, the law of armed conflict has almost exclusively focused on the protection of human beings. The present article is the first ever in-depth study of how the law of armed conflict applies to animals and fills a serious gap in the literature. The problem has become of great significance in the light of the public opinion’s increasing sensibility towards animal welfare and the emergence of animal rights theories. The main purposes of this article, then, are to assess whether the existing rules of the law of armed conflict provide adequate protection to animals and to highlight the fault lines in the law. The article distinguishes the general provisions of the law of armed conflict, i.e. those that were not adopted with specific regard to animals but the application of which might restrict the killing and injuring of animals, from the provisions that specifically provide protection to animals. The analysis essentially focuses on the killing and injuring of animals in the conduct of hostilities, and only incidentally refers to the exploitation of natural resources, pillage, and seizure of property in occupied territories.