The ethical acceptability of animal research is typically evaluated on a case-by-case basis. Legislation such as Directive 2010/63/EU on the protection of animals used for scientific purposes provides guidance for ethical evaluation of animal use proposals but does not dictate the outcome, leaving this determination to the ethical review committees of individual institutions. The authors assess different ethics models and how these are reflected in the guidelines of Directive 2010/63/EU. They also describe a matrix for carrying out harm-benefit analyses of animal use proposals, which they identified by examining the practices of three ethical review committees in the Netherlands. Finally, they discuss how this matrix can be applied by ethical review committees at other institutions.