This article is about the Republic of Ireland's M4.
For the British road that runs between London and Swansea, see M4
.For the unbuilt Northern Irish road with this number , see M4 (Northern Ireland)
The M4 is the motorway-standard part of the N4 route from Dublin to Sligo.
The M4 extends from J5 at Weston in County Dublin to J13 at Heathstown in County Westmeath.
- J5-J8 opened in 1994 as the "Leixlip Maynooth Kilcock bypass", albeit numbered as J2-4. What is now J6, numbered then as J2a, opened in 2003.
- J9-12 opened in 2005. This section of road is tolled.
- J12-13 also opened in 2005 but as D2AP. It was redesignated as motorway in 2009.
- Enfield Services opened in 2010