Grand National jockeys offered their racing tips to youngsters on a visit to Alder Hey Children's Hospital in Liverpool.
Among the stars to take time out from their training schedule were last year's champion AP McCoy, Ruby Walsh, Daryl Jacob and Aiden Coleman.
They spent about an hour at the hospital's oncology unit, chatting to the children and their parents.
McCoy said the visit "really put things into perspective".
The jockey, who with retired champion Mick Fitzgerald is a patron of Alder Hey's Imagine Appeal, said: "I never fail to be moved by the bravery of these children and their families.
Shelley Ball, whose five-year-old son Nathan is undergoing treatment for Langhan Cell Histiocycosis, said: "Nathan has been very excited all week.
"He doesn't really know about horse racing but kept asking when the 'jackies' would be coming."
Mrs Ball, from St Helens, added: "I can't describe what a boost it has given him, and me."
Becca Bate, 15, from Speke in Liverpool, got some hot tips for the Aintree meeting.
Her mother, Emma Paulson, 31, said: "Becca has Ewing Sarcoma but she has been responding well to treatment.
"She asked all the jockeys which horses they were riding and which were the best to have a flutter on.
"As soon as they left she dispatched her dad down to the bookies with her pocket money."
Jenny Lee, whose nine-year-old daughter Catherine has bone cancer in her leg, said: "I think it's great that they all came down today.
"The visit has really lifted the whole place."
Christine Done, fundraising manager at the hospital, said: "Some of these children are very poorly and something like this can really give them a lift for days and weeks to come."
The hospital's Imagine Appeal is the official charity partner for the Grand National meeting.
The jockeys also took part in a singing challenge to raise money for the cause.