Simple SummaryIn many countries, the approval of animal research projects depends on the decisions of the ethics committees which review the projects. Since the efficiency of the protection of experimental animals greatly depends on the performance of the ethics committees, its regular assessment is crucial. This paper reviews the results of studies assessing the performance of the ethics committees, and emphasizes the importance of outcome assessment in the evaluation of the performance of ethics committees.AbstractIn many countries the approval of animal research projects depends on the decisions of Animal Ethics Committees (AEC’s), which review the projects. An animal ethics review is performed as part of the authorization process and therefore performed routinely, but comprehensive information about how well the review system works is not available. This paper reviews studies that assess the performance of animal ethics committees by using Donabedian’s structure-process-outcome model. The paper points out that it is well recognised that AECs differ in structure, in their decision-making methods, in the time they take to review proposals and that they also make inconsistent decisions. On the other hand, we know little about the quality of outcomes, and to what extent decisions have been incorporated into daily scientific activity, and we know almost nothing about how well AECs work from the animal protection point of view. In order to emphasise this viewpoint in the assessment of AECs, the paper provides an example of measures for outcome assessment. The animal suffering is considered as a potential measure for outcome assessment of the ethics review. Although this approach has limitations, outcome assessment would significantly increase our understanding of the performance of AECs.