Three men are being let out of prison for a day to run the London Marathon.
The prison said the three men have committed low risk offences
It is the first time that prisoners from Standford Hill on the Isle of Sheppey, Kent - a Category D open jail - have competed in the race.
Physical education officer Sean Harding said there were no concerns that the prisoners might abscond.
Stanford Hill governor Kieron Taylor said all offenders were encouraged to give something back to the community. The men are raising funds for charity.
Andy Watts and Steve Sampson are running for Frank Bruno's charity for disabled children and the President's Sporting Club, which provides sports equipment and opportunities for children with disabilities.
Two of the men committed theft-related offences and one was jailed for perjury.
Richard Davis is raising money for the South Asia Earthquake Appeal.
They will be driven to Greenwich, south-east London, near the start of the race on Sunday morning.
Mr Harding, who has trained the trio, will be there to cheer the runners on, before picking them up at the finishing line.
He said the men came up with the idea to run and had been training for months.
Support from governor
Mr Taylor said: "Offenders are encouraged to give something back to the community so we are delighted to support these three men who are running in the London Marathon to raise money for charity.
"The three offenders have all committed low risk offences and have been fully risk-assessed for their suitability to take part in such an event.
"Standford Hill is an open prison and plays a vital role in the resettlement and rehabilitation of prisoners to lay the foundations for a smoother re-integration into the community.
"The aim of this is to reduce re-offending and ultimately to protect the public."