A leading HRT specialist says that he has prescribed male sex hormones to female politicians to help them "compete" with men.
The Commons chamber: A male environment
However, attempts by national newspapers to find a woman MP prepared to admit having such an implant have so far failed.
Women do naturally produce testosterone - but in smaller quantities than men.
Just as levels of female sex hormones can fall away, it is suggested that the same can happen to levels of testosterone in women.
Experts say that this may result in a reduced sex drive - and it has been associated in some studies with a fall in confidence.
Writing in the New Statesman magazine, Dr Malcolm Whitehead, who specialises in hormone replacement therapy, said he had been approached by a number of female politicians at his Harley Street Practice.
"I have prescribed testosterone implants for female politicians who want to compete better with their male colleagues in committee meetings and parliamentary debates.
"They claim the hormone boosts their assertiveness and mekes them feel more powerful."
The report instantly led to speculation in Westminster about who might have tried the implants.
Most female MPs approached by national newspapers did not admit doing so.
Environment, Food and Rural Affairs Secretary Margaret Beckett told the Daily Mail: "Women don't have to be like men to be successful."
The use of testosterone supplementation in women remains controversial.
Some doctors argue that it has no effect, and others even say it may be harmful.
Women who have an imbalance leading to higher levels of testosterone in their blood do suffer from symptoms such as acne, obesity and excess body hair.
However, an implant would not raise levels to anywhere near this extent.