The MoonWalk 2012, organised by Walk theWalk in aid of breast cancer has started in London with approximately 15,000 women actually taking part in the event.
The event is somewhat unusual, for a sponsored walk, in that it takes place at night and the vast majority of the participants choose to walk in bra tops and tee shirts.
This is the 15th year of MoonWalking and organisers say will be a record year.
Some top tweets from the march:
Pictures: 1 - @xLadyGardenx, 2 - @TheMaggieDoyle