Ruislip-Northwood was a borough constituency represented in the House of Commons of the UK Parliament from 1950 to 2010 that elected one member (MP) by the first past the post system of election. It was centred on the districts of Ruislip and Northwood in the London Borough of Hillingdon.

The seat returned each of three Conservatives who stood in turn. Its narrowest majority was 17.3% in 1997, over the Labour Party candidate.

This represented the northern half of the earlier Uxbridge constituency which was divided into two following house-building in the area in 1950.

Ruislip-Northwood was a constituency that as such covered slightly elevated and gently hilly outskirts of West London, beginning 12 miles (19 km) WNW of Charing Cross.^[1]

All three of its successive Members of Parliament were Old Etonians and as the majorities they received were non-marginal, with their contributions the seat was throughout its elections a safe seat.

Almost all of its area has been succeeded by Ruislip, Northwood and Pinner.

1950–1974: The Urban District of Ruislip-Northwood.

1974–1983: The London Borough of Hillingdon wards of Eastcote, Haydon, Manor, Northwood, Ruislip, and South Ruislip.

1983–1997: The London Borough of Hillingdon wards of Bourne, Cavendish, Deansfield, Eastcote, Manor, Northwood, Northwood Hills, Ruislip, and St Martins.

1997–2010: The London Borough of Hillingdon wards of Bourne, Cavendish, Deansfield, Eastcote, Harefield, Manor, Northwood, Northwood Hills, Ruislip, and St Martins.

The constituency consisted of the northern part of the London Borough of Hillingdon.

• List of parliamentary constituencies in London