Abstract: Terrorism, which as a term defies a very clear definition, is not a newborn phenomenon. And although it is ubiquitous in all societies, its sources or motives -as well as related methods- vary greatly over time and space. The Irish Republican Army (IRA) constitutes a typical example of the anticolonial wave terrorist groups struggling for self-determination after the collapse of empires in the twentieth century. As such, it belongs to the so-called “old” or traditional terrorism as opposed to al Qaeda or ISIS, which represent what are said to be “new” terrorist groups. The reasons that prompted the rise and development of the IRA as a terrorist group and its key characteristics have been much discussed in the related literature. The strengths of the IRA, that is the factors that made it long-lasting and successful, as well as its shortcomings along with their potential effects have been adequately researched. Similarities and differences between the IRA and other terrorist groups, especially in the light of their core values, their followed strategies and the nature and effectiveness of counter strategies on governmental level have also been well recorded in the terrorism literature. Even though there exist a few studies focusing on the economic repercussions of terrorism, the economics of the IRA both from the input (terrorist financing) and the output (economic consequences of terrorism) side do not seem to have attracted much attention. This paper aims to explore the economic impact of the IRA by employing an input-output approach. Desk research was used to gather and analyze data from various sources, such as books, journals, reports and relevant websites. The results suggest that more recent literature points to a plethora of non-US fund-raising mechanisms for the IRA, contrary perhaps to the popular history or early studies on the subject. The results also indicate that the IRA, with its use of violence, negatively affected in multiple ways the British economy and, even more, that of Northern Ireland, not to mention that of the Irish Republic. The results are discussed in terms of three types of economic impact, namely direct, indirect (or, intangible/secondary) and “other” costs of the IRA terrorist attacks, always bearing in mind the short-run versus long-run perspectives.