The R150 connects the R167 at Drogheda in County Louth to the R153 at Kentstown in County Meath by a curious course which involves an initial stretch running east from Drogheda for some 4 km in the direction of the mouth of the River Boyne, followed by a turn to the right taking the route south-by-southeastward through the Irish Sea coast village of Bettystown for about 7 km, before another sharp swing to the right at Laytown (and the mouth of the River Nanny) sets the bearing for a final 22-km westward run – exactly parallel to the road's first section, but heading in the opposite direction – crossing the M1 (no junction) and the N2 on the way.
R150 near Julianstown - roadworks to realign and widen the carriageway
This same course was followed by the L125 in the old (pre National and Regional Roads) system, and appears to have been taken over wholesale from it.