In 2019 the Mud Run had more than 550 participants.
Brady said the event has grown massively over the eight years.
"The Mud Run is our main annual fundraiser for Flemington School, and each year it has grown bigger, better and muddier."
The courses can be run individually or as a team.
Plenty of food and coffee will be available alongside spot prizes for the best costumes.
Weather-permitting, there'll also be Flemington School's famous lolly scramble, with a fly-over from the pink plane at Rural Air Work.
Brady said there'll even be some horse action to watch in the afternoon.
"After the race the Wanstead Polo Club will be kicking off their new season, so people can stay, grab a bite to eat and watch some chukkas," Brady added.
Showers will be available for mud-covered participants – a towel and clean clothes will be needed.
Registration opens at 8.45am, a pre-race briefing will be at 9.45am, followed by a 10am start.
Children under the age of 7 must be accompanied by an adult at all times on the course.
Flemington School will be running fundraising auctions in the lead-up to race day.
For more details and online entry visit www.flemingtonmudrun.com. You can also visit Facebook / Flemington Mud Run.