Mayo is a parliamentary constituency represented in Dáil Éireann, the lower house of the Oireachtas (the Irish parliament).

The constituency elects five deputies (Teachtaí Dála, commonly known as TDs) on the system of proportional representation by means of the single transferable vote (PR-STV).

At the 2002 general election Fine Gael suffered its worst electoral performance ever, losing 23 seats nationally, a figure larger than expected and with its overall vote down 5%.

Enda Kenny came close to losing his seat and even went so far as to prepare a concession speech.

Its largest towns are Castlebar, Ballina, Westport, Claremorris and Ballinrobe.