Background: Good performance in a summative assessment does not always equate to educational gain following a course. An educational programme may focus on improving student's performance on a particular test instrument. For example, practicing multiple choice questions may lead to mastery of the instrument itself rather than testing the knowledge and its application. We designed an assessment strategy that consistently valid and reliable that would fit with the students with a range of 27 nationalities with a different institutional, cultural and educational background in this totally online masters programme in transplantation. Methods: Based on the published evidence, we analyzed 2 main assessment domains: (a) self-assessment and (b) peer-assessment. We compared them with traditional teacher-led assessment considering the diversity of students. Conclusion: We conclude that traditional teacher-led assessment supplemented by self-assessment is a strong drive in the learning process in this on-line course, whilst peer-assessment is challenging and associated with many flaws giving the diversity of our students. Peer-assessment may be unreliable and not valid due to the difference in the institutional background and variation in experience between the students.