Sexism is preventing women from gaining the top jobs in England's secondary schools, Tristram Hunt has said.
The shadow education secretary warned of a "gender challenge" and claimed that the numbers of female teachers becoming school leaders was falling.
Figures suggest that in 2012, just under two thirds of headteacher posts in state secondary schools were held by men, with a third filled by women.
In a speech to the Association of School and College Leaders (ASCL) annual conference in Birmingham, Mr Hunt said: "When it comes to the appointment of secondary school leaders, we have, like so many other sectors, a gender challenge.
"The statistics are stark. Despite the fact that 62% of all teachers working in secondary education are women, when it comes to head teachers that figure drops to just over a third. And it is falling."
He added: "What is more, when you hear some of the shocking testimony collected by the Future Leaders charity - schools not following proper legal process; comments about 'too much oestrogen flying around'; governors' recruiting based upon gender - then it does seems to paint a picture of prejudice in some of our secondary schools.
"There is simply no place in our society for this kind of casual, everyday sexism and we must confront it in our schools system whenever we encounter it."
Mr Hunt told delegates that schools could miss the chance to appoint the best person for a job, potentially affecting pupils, if they discount candidates because of their gender.
"School governors must uphold their moral and legal duties when it comes to fair access to leadership. And where this is not happening, we must all shine a spotlight," he said.
ASCL general secretary Brian Lightman said: "Any recruitment panel for any job needs to be fully trained in the equal opportunities requirements and needs to be mindful of those processes."
He said that he was sure there were examples of discrimination, adding "we need to make sure that everything possible is being done to eradicate that".