There were exclamations of excitement and giggles galore as window cleaners dressed as cartoon characters Leonardo, Donatello, Michelangelo and Raphael made a surprise visit to the Centenary Hospital for Women and Children on Monday.

About a dozen children waited patiently for the surprise visitors to appear before the workers, who had ditched their overalls for green-coloured suits and coloured bandanas, dangled from the rooftop and performed gravity-defying backflips.

Rope Access Engineering general manager James Howe said it was the second time staff at the abseiling company had dressed up – last year workers transformed into superheroes – as they cleaned the hospital's windows.

"Everyone was really on board with it, there was a bit of a fight to see who'd get to do it.

"It's priceless, you can't even describe it."

It was part of a trend that has seen window washers dress as superheroes and other novelty characters to turn frowns upside down at children's hospitals around the world.

Ronald McDonald House Canberra executive officer Michelle McCormack said there was plenty of excitement in the room and children remained in high spirits for the rest of the day.

"It was amazing. The opportunity for kids to have that kind of experience when they're sick themselves or they have a sibling receiving treatment – it just takes their minds off things for awhile."

Ms McCormack said she enjoyed observing the joy on parents' faces as they watched their youngster's faces light up, and the event was a welcome boost for staff as well.

It also created positive and lasting memories for kids at the facility, which provided a home away from home for seriously ill children and their families.

"What I see is that it sticks with them and they remember it if they come back, if they come back and visit they'll say 'I was here when the ninja turtles were here, or they'll ask where they are," she said.

"It just brings smiles to faces that would otherwise not be there."