Mural paintings are an integral part of urban spaces of Northern Ireland main cities’ popular areas.This work is an edited and actualised version of a master degree research conducted in 2009 for the department of Irish Studies of Rennes2 University. It puts murals’ painting back in its historical context and deals with the origins of such practices in both communities. An insight in chosen areas of Belfast and Derry-Londonderry enables an understanding of the motivations behind the use of themes according to specific areas. Besides, the analysis of those themes indicates that they contribute to maintaining people from these areas in a sectarian mind. Last but not least, it questions the durability of murals in a quasi pacified Northern Ireland with the study of a governmental regeneration programme aimed at replacing violent and aggressive murals and the response to this programme.