Margaret Beckett will not stay foreign secretary under new Prime Minister Gordon Brown, the BBC understands.
Margaret Beckett has been Foreign Secretary since 2006
It is not yet known if she will be given another job in government, or return to the backbenches.
Mrs Beckett has been in the Cabinet since Tony Blair came to power, including a long stint as Environment, Food and Rural Affairs secretary.
Health Secretary Patricia Hewitt is also out, with Mr Brown to reveal other changes over the next 24 hours.
BBC Political Editor Nick Robinson said Mrs Beckett had been informed by Mr Brown that he did not want her to remain in the job.
Commons leader Jack Straw was said to be keen to return to the Foreign Office - a post he held from 2001 until Mrs Beckett took over in 2006.
There has also been speculation that Environment Secretary David Miliband could be interested in the job.