They are swapping their scrubs for their running gear.
A team of 15 - made up of doctors, nurses, pharmacy, lab and admin staff at the Children's Haematology/Oncology Unit in the Royal Belfast Hospital for Sick Children - were all due to run the Belfast Marathon this weekend in three relay teams.
But after it was cancelled as a result of the coronavirus, they decided to still run their distances around their local areas - in a safe, socially distanced way. The shortest distance is four miles and the longest is 6.9 miles.
So far they have raised more than £1,500 in aid of the Children's Cancer Unit Charity.
Among those taking part is Dr Lyndsey Thompson from Belfast.
She said: "We were keen to run the marathon for the Children's Cancer Unit Charity, the charity attached to our unit. We are very aware that as doctors and nurses and as a whole team we provide medical care to all of our patients and their families. However, that is only part of their cancer journey.
"There is so much more that they need. They need emotional support, psychological support, financial support and just bringing a bit of joy to an awful situation, and that's where the charity comes into it.
"We felt that by running for the charity it was another way we could support our patients and their families to get through their journey."
Dr Thompson said that during the ongoing pandemic they have been able to continue providing the medical care as normal for their patients - but they are constantly concerned about infection in the vulnerable youngsters.
"That makes all of their journeys harder, it makes the medical issues more concerning and puts the families under an awful lot of stress and pressure as well as anxiety levels.
"So, even more so, that's where the charity comes in to help them."
On behalf of the Children's Cancer Unit Charity, Felix Mooney added: "This team does the most incredible job every day, caring for young patients and families affected by childhood cancer, on the wards and at home ... but we are particularly thankful for their support this weekend."
To donate visit https://www.justgiving.com/fundraising/chu-athletes