'Animal Ethics Dilemma' is a freely available computer-supported learning tool (www.animalethicsdilemma.net or www.aedilemma.net) which has been developed primarily for veterinary undergraduates but is applicable also to students in other fields of animal science. The objectives of the computer program are to promote students' understanding of the ethics related to animal use, to illustrate ethical dilemmas that arise in animal use, to broaden students' moral imagination, and to enable students to differentiate between types of ethical argument. The program comprises five case studies: (1) the blind hens; (2) ANDi the genetically modified monkey; (3) euthanasia of a healthy dog; (4) animal slaughter; and (5) rehabilitation of seals. Special consideration has been given to enhancing the pedagogic value of the program. Students can control their learning by selecting a variety of ways to explore the program; for example, they can navigate the program using the 'Assist Me' option, which explains the basis of the ethical arguments. Reality text provides details of real events on which the case is based, and a glossary of terminology is available for the students to explore. Selected access to a case template is also available, enabling students and teachers to create their own case studies. Evaluation of the program has been ongoing during its development.