Real-life, complex problems often require that decisions are made despite limited information or insufficient time to explore all relevant aspects. Incorporating authentic uncertainties into an assessment, however, poses problems in establishing results and analysing their methodological qualities. This study aims at developing a test on clinical decision-making in veterinary medicine and establishing its reliability and validity. The test is based on the script concordance test method and covers a large sample of authentic cases and uncertainties. The answer key was compiled with reference to the professional judgements and decisions of a panel of experienced practitioners. From a substantive appraisal of the cases and items, the analysis of the test results and the responses from the experienced practitioners, it is concluded that this test validly represents the problems, decisions and uncertainties of clinical practice. In spite of the hindrances caused by the uncertainties included in the test, the reliability and validity of the test and its results could be evaluated and proved to meet measurement criteria. (Contains 2 tables and 3 figures.)