The IRFU Women's Interprovincial Series, previously known as the IWRFU Interprovincial Championship, is the top level women's rugby union competition in Ireland. It is organised by the Irish Rugby Football Union. It is the women's equivalent of the IRFU Interprovincial Championship. The competition takes place every December and features four teams representing Connacht, Leinster, Munster and Ulster. The competition effectively acts as a selection trials process for the Ireland women's national rugby union team that competes in the subsequent Women's Six Nations Championship. Since 2016 the IRFU has also organised a similar under 18s competition.