Hertsmere Jewish Primary pupils Ruby and Bella Margolis have already earned £1,750-plus for Aims2Cure,a charity backing research into multiple sclerosis.
As they explain on their online fund-raising page: "We have decided to do the fun run as our daddy suffers with multiple sclerosis. We see the daily struggle our daddy has to go through and how brave he is."
Adam Margolis, 36, was diagnosed 10 years ago. He said he was "100 per cent proud" of his daughters for coming up with the idea, fundraising and even convincing cousins Ziggy and Macy to join them in the 1k event.
"They only know me with MS. They're very caring, very understanding."
He said that MS was "a horrible neurological disease where every day it gets worse and worse - until a drug is found to stop the progression".
As its title implied, the aim of the charity his girls were running for was "to find a cure, so the intentions are fabulous. It's a phenomenal charity."