This article examines poor law hospital reform during the 1920s and 1930s. Northern Ireland’s failure to dissolve the poor law system until the 1940s is viewed as one of its major failures in health policy, as the other countries in Britain and Ireland had broken up the system by 1929. Recent historiographical examinations of interwar healthcare have challenged older negative accounts of the period and instead identified diverse, vibrant and expanding health systems. Much of this has concentrated on English and Welsh health systems or comparisons between large, industrialized nations. Research remains lacking on the trajectory of healthcare in smaller, nascent countries that witnessed political realignment and new settlements during an era of transformation in empire. Irish partition and the establishment of two new states – Irish Free State and Northern Ireland – represented a major reshaping of the British Empire. This article concentrates on Northern Ireland and argues that where local workhouse infirmaries were transformed into district hospitals local authorities brought positive improvements in healthcare evident in many countries. Such improvements were, however, limited to the north-east and the west and south of Northern Ireland, which were marked by political and religious tensions, witnessed limited reform. Local authority policy innovation was thwarted by state interference in local government, which included the temporary dissolution of dissenting Nationalist authorities and gerrymandering of electoral boundaries. This article also argues that the failure to dissolve the poor law was a result of limited medical professional interest in reform. Northern Ireland’s powerful medical profession was key to shaping the direction of Northern Irish policy. This was a result of the devolved administration’s limited expertise in policy making and the dominance of the constitutional question and Nationalist–Unionist divisions in politics.