Abstract. In this paper we describe our experience of using three different animation systems. We searched for and decided to use these tools in the context of a project which involved developing formal versions (in Z) of informal requirements documents, and then showing the formal versions to people in industry who were not Z users (or users of any formal techniques). So, an animator seemed a good way of showing the behaviour of a system described formally without the audience having to learn Z. A requirement, however, that the tools used have to satisfy is that they correctly animated Z (whatever that may mean) and they behave adequately in terms of speed and presentation. We have to report that none of the tools we looked at satisfy thes...