This article critically reviews the case law, guidance and standards related to the provision of expert psychiatric evidence in immigration and asylum cases in the UK. It discusses the potentially complex and medico-legally challenging process of psychiatric evaluation of asylum seekers, and the implications of the presence of psychiatric disorders for issues such as the individual's ability to give oral evidence in court, immigration detention, fitness to fly, removal, deportation, ability to reintegrate into the destination country and appeal rights. To give context to the discussion, it outlines the asylum process in the UK from claiming asylum, initial screening and the ‘substantive interview’ to, if a claim is rejected, appeal to the First-tier Tribunal (Immigration and Asylum Chamber), detention and the removal process.