Among different methods which evaluate students' performance and learning results at Master programmes in International Arbitration / Alternative Dispute Resolution is an open book exam. It helps check student's knowledge as well as application of cognitive / intellectual / thinking skills and practical / professional / subject skills. Here examinees are allowed to use educational materials during the exam but they succeed only in case of thorough preparation of both a teacher and students, namely: adaptation of students to an open book exam format; development of necessary guidelines; determination of the targets which should be achieved; establishment of objective marking criteria; tailoring principles for reference materials selection; application of effective data retrieval methods and so on. A teacher must be ready to combat some potential problems which can arise while organizing an open-book exam: complete reliance on the prepared materials; poor time management of students; unfair competition (falsification of the material); corruption; cheating. In spite of some disadvantages, there is a list of an open exam advantages, prerogatively, stimulation of student intellectual vigour and application of theory into practice. An open book exam places the focus on higher abilities such as analysis, synthesis, compilation, interpretation, etc., making a student think deeply and creatively. The most important condition for successful open book exam is to outline the materials permitted for utilization in the classroom and insure their availability to the students, guaranteeing equality to every participant. It is proved that there is an urgent necessity to apply an open book exam as an assessment method at Master degree programmes in International Arbitration and Alternative Dispute Resolution.