Northern Ireland (NI) has been one of the central issues in Brexit. Yet, it barely featured in the discussions in the run up to the EU Referendum in 2016. This blind-spot regarding NI has been a long-standing feature of social science research on the UK. This article examines the NI blind-spot, with a particular focus on its operation in ethnic and racial studies. The article examines the NI blind-spot as a methodological issue, through an application of, and then critical reflection on, the concept of "methodological nationalism". The article also examines the NI blind-spot in relation to two key areas of applied ethnic and racial studies: immigration and "race relations". We conclude by reflecting on the implications of our analysis for ethnic and racial studies in, and of, the UK.