New figures released Labour reveal that only 7% of the total TV workforce (on and off-screen) are women over the age of 50.
Meanwhile, the majority of TV presenters who are over 50 are men (82%).
Miriam O'Reilly, who won an employment tribunal against the BBC on the grounds of ageism, said:
These figures raise the obvious questions of where have all the older women gone and why did they go? Was it their choice to leave their jobs or was it a decision forced upon them?
The broadcasters say they are committed to the fair representation of older women, but the figures don't bear that out.
I'd like to know the reasons why so many talented women have disappeared, while their male counterparts have grown older and still have their jobs.
Women on television are affected by a "combination of ageism and sexism" that does not apply to men, according to new figures released by Labour.
Harriet Harman, shadow secretary of state for culture, media and sport, asked the six main UK broadcasters how many older women they employ on screen and behind the camera.
The findings were that while the majority of over 50s in the UK are women (53.1%), the overwhelming majority of TV presenters who are over 50 are men (82%).
It was discovered that only 7% of the total TV workforce (on and off-screen) are women over the age of 50.
Ms Harman said: "The figures provided by broadcasters show clearly that once female presenters hit 50, their days on-screen are numbered.
"It is an encouraging first step that broadcasters have been open in providing these statistics. Their response shows that they all recognise that this is an important issue that needs to be addressed.
"I will be publishing these figures annually so we are able to monitor progress."
Ms Harman will also be holding a roundtable with broadcasters in the House of Commons today to challenge them to take action.