Caithness and Sutherland was a county constituency of the House of Commons of the Parliament of the United Kingdom from 1918 to 1997. It elected one Member of Parliament (MP) by the first past the post system of election.

The constituency was created by merging the constituencies of Caithness and Sutherland and the Dornoch and Wick components of the Wick Burghs constituency.

In 1997 the constituency was superseded by the creation of Caithness, Sutherland and Easter Ross, which merged Caithness and Sutherland and the Easter Ross area of Ross, Cromarty and Skye.

Caithness and Sutherland was geographically one of the largest constituencies in the United Kingdom, as well as the most northerly constituency on the mainland (only the island constituency of Orkney and Shetland was further north).

The creation of Caithness and Sutherland as a single constituency was a part of a package of boundary reform also affecting many other parts of the United Kingdom. The reform was the first since the Redistribution of Seats Act of 1885, and its main aim was to make constituencies more equal in terms of the sizes of their electorates.

At the time of the 1918 general election, Sir Leicester Harmsworth had been MP for the constituency of Caithness since the 1900 general election.

In the general election of 1997, Robert Maclennan was elected MP for the then new constituency of Caithness, Sutherland and Easter Ross, a seat he held until retiring from parliament at the 2001 general election.