Over 17,500 runners will hit the pavements of Belfast this morning for the annual City Marathon with the weather expected to stay dry for the May Day event.
The runners will start the marathon at around 9am with those participating in the Wheelchair Race beginning shortly before the main marathon event.
Last year 9,950 competitors took part in the relay race and organisers say the event is even more popular this year.
There is also a fun run and eight mile walking event for those not quite up to the full marathon.
This year's official nominated charity is Mencap with the race starting at City Hall and meandering through the streets of north, east and west of the city before finishing at Ormeau Park in south Belfast.
Drivers can expect disruption between 6.30am and 11am in the city centre, in east Belfast and on the Sydenham bypass; between 9.30am and 1.30pm on the Shore Road and the Dargan Road; and between 11am and 3pm on Oxford Street, the Ormeau Road and the Ravenhill Road.
Many of the runners will take to the roads to raise money for their selected charities raising thousands of pounds for good causes.
Up to 130 people are to run the relay race to raise money for the family of a west Belfast man who died from a heart attack aged just 29. Tony Campbell, passed away suddenly at the end of January leaving behind his girlfriend Roisin and newborn baby son Conal.
Members of Tullymore Swifts, who Tony played for, and members of GymCo in Finaghy where he trained are coming together to raise money.
Suzanne McCullagh from North Belfast is running the marathon to raise much needed funds for PIPs which provides suicide prevention and bereavement support services, in memory of her nephew John Perry who took his own life ten years ago.
Four relay teams are running to raise money for Duchenne Muscular Dystrophy, among them Michael Braiden whose three-year-old son Niall was recently diagnosed with the illness.
Margaret Smyth from Twinbrook, but now living in Ardglass, is running the marathon for a Meningitis charity after her best friend Naomi Baillie contracted the illness.
Louise and Declan McGinley from Ardboe are running the full marathon to raise money for the Motor Neurone Disease Assocation.
The staff from Baker Tilly Mooney Moore are running the relay race for Action Ability.
And Aaron Trainer from west Belfast is among a relay team raising money for four-year-old Jaxon Kane to help pay for specialist behavioural training, Jaxon suffers from autism.