The purpose of this review was to examine the practice of oral assessment in postgraduate medical education in the context of the core assessment constructs of validity, reliability and fairness. Although oral assessment has a long history in the certification process of medical specialists and is a well-established part of such proceedings for a wide range of specialties in most countries, there remains concern regarding its use. Therefore, there has been some move away from oral assessment for postgraduate medical education in some countries. This review also highlights the complexity of oral assessment as an examination format, partly through a consideration of the six dimensions of oral assessment, and raises concerns about the validity, reliability and fairness of such an assessment procedure for the award of certification of completion of the specialist training. Supporting high quality published research into examination practices and outcomes and acting on the findings of such research is needed urgently to allay concerns about the transparency and fairness of these examinations, especially when assessing international medical graduates. The article concludes by proposing 15 conditions under which oral assessment is valid, reliable and fair.