Their six-year-old daughter, Ruby, was diagnosed with acute lymphoblastic leukaemia two years ago and they have spent most of that time visiting her in Randwick Children's Hospital, or travelling from their Mount Warrigal home to Sydney for treatment.

"It was like being dragged into a world you have no idea about," father Steve said.

He said for the first few months, Ruby was gravely ill following intensive chemotherapy.

"But that is where we learned about the Starlight Room and the wonderful people who spend their time trying to make life under treatment bearable," he said.

Ruby is now in remission.

However, one moment will stay with her parents forever.

It was about seven weeks into intensive chemotherapy and Ruby was feeling weak and scared.

Mr Marriott, wife Cindy and Ruby's sister, Gabrielle, wanted to reassure and comfort her.

"It was a great relief when towards the end of a performance in the Starlight Room that Ruby, ever so slowly at first, started to curl a corner of her lip, then both corners," he said.

"Then we saw teeth, then we heard Ruby laugh.

"We didn't realise at first the significance of what we were seeing but it only took a few seconds to sink in, how much we missed seeing our daughter be happy - be normal.

"With one smile, Ruby had given us the strength and motivation to carry on."

After two years of treatment, Ruby has improved , with help from the work of the Starlight crew.

"They make children's, and families, lives bearable and provide that wonderful distraction both the kids and us needed," Mrs Marriott said.

The crew also visits children with face-painting, balloons and magic tricks.

The organisation is celebrating its 25th birthday with Starlight Day on Friday.

Donations can be made at starlightday.org.au.