Labour figures have reacted with outrage after David Cameron told a female opposition frontbencher to "calm down, dear".
The Tory leader was answering a question from Labour leader Ed Miliband about NHS reforms when he was interrupted by loud female shouting.
"He's no longer an MP because he lost the election I'm afraid because of a Conservative candidate," Mr Cameron said, referring to the former MP Howard Stoate.
"He's stood down!" a female voice, later identified as Angela Eagle's, replied.
The prime minister responded: "Calm down dear, calm down, calm down. Listen to the doctor. Calm down and listen to the doctor."
The phrase "calm down dear" was made famous by pleasure-loving film director and critic Michael Winner.
Mr Cameron attempted to continue reading the quote but eventually gave up, instead adding: "I said calm down. Yes, calm down dear - I'll say it to you if you like... I'm not going to apologise, you do need to calm down."
Labour sources responded by calling the remark "patronising", "insulting", "unprime-ministerial" and "sexist".
A party spokesperson said: "This isn't a laughing matter." Backbencher Chuka Umunna tweeted: "The mask slips: at PMQs just now Cameron says "Calm down dear" to either Angela Eagle or Yvette Cooper. Totally unbecoming of a PM."
Kevin Brennan added: "Cameron's mask slips again this time to reveal his patronising view of women."
Labour's deputy leader Harriet Harman commented afterwards that Mr Cameron's "contemptuous response" to Ms Eagle showed a "patronising and outdated attitude to women".
She added: "Women in Britain in the 21st century do not expect to be told to 'calm down dear' by their prime minister."
The ensuing row in the Commons chamber brought exchanges between Mr Cameron and Miliband to a premature end.
Speaker John Bercow twice intervened, rebuking MPs and telling them their behaviour left "a very bad impression on the public as a whole and the other people".
Tory candidate quits over sexism
Mr Cameron was not the only Conservative politician getting in trouble over allegedly sexist comments, however.
The Evening Standard newspaper revealed a Conservative candidate standing for Thanet council had resigned from the party after calling local Thanet girls "slags, hoes, brasses and bheads".
Payam Tamiz, 21, who was standing for the Salmestone ward, was judged to have used "outrageous and unacceptable" language by a party spokesman.
Labour MP Heidi Alexander seized on the comments as further evidence of the Tory party's inbuilt sexist nature.
"People will rightly be asking how someone with such disgraceful views came to be selected as a Conservative candidate in the first place," she said.
"David Cameron should apologise and make clear that there is no room for sexism in Britain today."
Miliband picks health and the economy
Earlier exchanges in PMQs had focused on the economy and NHS reforms. Mr Miliband had claimed the economy had "flatlined in the last six months", after GDP figures released this morning suggested economic stagnation over the last three quarters.
Mr Cameron attacked Mr Miliband for "talking the economy down" and accused him of hoping for the economy to shrink.
"We've got debts, tragically because of what we've inherited, but we've got interest rates like Germany," he pointed out.
The Labour leader responded by criticising the content of the prime minister's answers.
"What world is he living in? What extraordinary complacency, what terrible complacency from this prime minister!" he responded.
The second set of questions, which culminated in the "calm down dear" remarks, focused on the coalition government's plans on the NHS.
"When you make changes in public services it is a challenge to take people with you," Mr Cameron said.
But he was riled by Mr Miliband's criticisms over waiting times and the no-confidence vote in health secretary Andrew Lansley passed by the Royal College of Nursing earlier this month.