Three recently developed and published schemes to evaluate the acceptability of proposed animal experiments are discussed and compared: 1. The model developed at the request of the Dutch Veterinary Public Health Chief Inspectorate by the Department of Animal Problems of Leiden University
(the 'Dutch Model'); 2. The model proposed by the Canadian, David G Porter (the 'Porter model'); 3. The model developed by the British Institute of Medical Ethics, published in 'Lives in the Balance: The Ethics of Using Animals in Biomedical Research' (the 'IME model'). It is concluded
that the Porter model although compact, does not have an acceptable level of discrimination; nor does it provide the researcher with any pragmatic tools to optimize the research design. The other models appear to be quite adequate for the different purposes for which they were developed. The
Dutch model was developed to guide the evaluation procedure at the level of local institution-based committees (ie internal evaluation by colleagues), whereas the IME model will serve the professional officers of the United Kingdom Home Office Inspectorate (ie external evaluation). Finally,
the pragmatic consequences of the three models are discussed with respect to two hypothetical cases.