Since the introduction of devolution in 1999 there has been a growth in comparative analysis of the National Health Service (NHS) as it has developed between England, Scotland and Wales. Several analyses have considered funding and policies on provision and performance, usually noting the difficulties in carrying out comparative evaluation. Few studies to date have included detailed analysis of Northern Ireland and this paper seeks to set out and analyse the organisation of the NHS in Northern Ireland. The focus is on the structures of the NHS as it has developed since devolution and relates to similar structures in the NHS in England, Scotland and Wales. The analytical approach in the paper uses the concept of policy copying to interrogate the structural and institutional organisation of the NHS in Northern Ireland. This facilitates an assessment of the degree of divergence between Northern Ireland and the other UK countries, and the nature and scope of policy copying. The article then seeks to explain the reasons for both policy copying and the rejection of policy copying, and how this may have led to identifiable policy deficiencies.