Prime Minister's Questions (PMQs, officially known as Questions to the Prime Minister, while colloquially known as Prime Minister's Question Time) is a constitutional convention in the United Kingdom, currently held as a single session every Wednesday at noon when the House of Commons is sitting, during which the prime minister answers questions from members of Parliament (MPs).

The Institute for Government has described PMQs as "the most distinctive and internationally famous feature of British politics." In the legislatures of the devolved nations of the UK, the equivalent procedure is known as First Minister's Questions.

Although prime ministers have answered questions in parliament for centuries, until the 1880s, questions to the prime minister were treated the same as questions to other ministers of the Crown: asked without notice, on days when ministers were available, in whatever order MPs rose to ask them. In 1881 fixed time-limits for questions were introduced and questions to the prime minister were moved to the last slot of the day as a courtesy to the 72-year-old prime minister at the time, William Ewart Gladstone, so he could come to the Commons later in the day. In 1953, when Winston Churchill (in his late 70s at the time) was prime minister, it was agreed that questions would be submitted on fixed days (Tuesdays and Thursdays).

A Procedure Committee report in 1959 recommended that questions to the prime minister be taken in two fixed-period, 15-minute slots on Tuesday and Thursday afternoons. The recommendations were put into practice under Harold Macmillan during a successful experiment from 18 July 1961 to the end of the session on 4 August. The very first question was delivered by Labour MP Fenner Brockway, asking to which minister the UK ambassador to South Africa would be responsible. In response to the prime minister's answer, Brockway said "May I express our appreciation of this new arrangement for answering Questions and the hope that it will be convenient for the Prime Minister as well as useful to the House?" PMQs were made permanent in the following parliamentary session, with the first of these on 24 October 1961.

The style and culture of PMQs has changed gradually over time. According to former Speaker Selwyn Lloyd, the now famous disorderly behaviour of MPs during PMQs first arose as a result of the personal animosity between Harold Wilson and Edward Heath; before this PMQs had been lively but comparatively civilised. In the past, prime ministers often opted to transfer questions to the relevant minister, and leaders of the opposition did not always take their allocated number of questions in some sessions, sometimes opting not to ask any questions at all. This changed during the premiership of Margaret Thatcher, when the prime minister chose not to transfer any questions to other members of her Cabinet, and Labour leader Neil Kinnock began asking more questions than his predecessors. His successor, John Smith, established the precedent of always taking his full allocation of questions.

One of Tony Blair's first acts as prime minister was to replace the two 15-minute sessions with a single 30-minute session on Wednesdays, initially at 3 p.m. but since 2003 at noon. The allocated number of questions in each session for the leader of the opposition was doubled from three to six, and the leader of the third-largest party in the Commons was given two questions as opposed to one question beforehand. The first PMQs to use this new format took place on 21 May 1997.

During the Conservative-Liberal Democrat coalition government from 2010 to 2015, Nick Clegg, the leader of the Liberal Democrats, as a member of the government, did not ask questions during PMQs. Instead, the leader of the second largest parliamentary opposition party at the time, Nigel Dodds of the Democratic Unionist Party (DUP), usually asked a single question later in the session, followed by at least one MP from another party such as the Scottish National Party or Plaid Cymru.

Backbench MPs wishing to ask a question must enter their names on the Order Paper. The names of entrants are then shuffled in a ballot to produce a random order in which they will be called by the speaker. The speaker will then call on MPs to put their questions, usually in an alternating fashion: one MP from the government benches is followed by one from the opposition benches. MPs who are not selected may be chosen to ask a supplementary question if they "catch the eye" of the speaker, which is done by standing and sitting immediately before the prime minister gives an answer.