More than 350 runners enjoyed the sunshine at the Hove Fun Run.
The fancy dress outfits included Fred Flintstone, his grandma and 101 Dalmations, as fundraisers jogged and walked 5km around Hove Park.
Neil Kilgour, Big Fun Run director, said: “The Big Fun Run is strictly for fun and all about easy relaxed exercise.
"The run isn’t timed so participants were motivated by the chance to get together with family and friends and do something healthy in the great outdoors.
“This isn’t about testosterone charged athletes charging home in a record time, it’s about mums with prams and dads with toddlers on their shoulders.”
He also said: “They’re family affairs with people across generations taking part.
“It’s not unusual to see a grandparent, mum and kids all at the starting line.”
Hove Park boasts 40 acres of matures trees and flowers as well as the fingermaze inspired by the Cretan labyrinth, so it was the perfect setting for the run.
The Big Fun Run in Brighton is among 17 Big Fun Runs across the UK staged from July until October, with the next run taking place in Southampton.
More than 7,000 people took part in Big Fun Runs last year and raised more than £200,000 for charity.
The Big Fun Runs have over 49 charity affiliations including Macmillan Cancer Support and the Multiple Sclerosis Society.
Sarah Coxhill, fundraising manager for Macmillan Cancer Support, said: “In Sussex 24 people every day are diagnosed with cancer.
“It’s our aim to make sure no one faces cancer alone but we can’t do this without the support of amazing people who fundraise for us so we’d like to say a huge thank you to all who took part.”
The event was organised by GSI Events, who also organise the Edinburgh Marathon Festival.