The Royal Hobart Hospital is celebrating ten years of clowning around.

The first Australian Clown Doctor pilot project was undertaken at the hospital shortly after the 1996 Port Arthur massacre, and the colourful characters became a permanent fixture a few years later.

Nurse Unit Manager Janine Sawford said they were a valuable tool.

"They are a huge distraction," she said.

"We use them for procedures in our treatment room, and they just make the ward fun and [create] laughter for all the children."

The program was inspired by American research on the benefits of humour at the Big Apple Clown Care Unit in New York.

There are now six of the colourful characters healing with humour twice a week, and 60 around the country.

Dr Do Little - actor Peter Dowling - said it was a rewarding job.

"I always think it's like 90 per cent pure joy and 10 per cent pure heartache, probably when you get to know really sick kids," he said.

Harrison Read is one of the young patients recently visited by Dr Do Little.

He said it made him feel better about being in hospital.

Clown doctors share patient stories. ( ABC News: Lauren Day )

"They make you laugh and they trick you, and do magic tricks," Harrison said.

"They're really nice, they make really sick people really happy, and it's good."

His father Jarrod appreciated the visit too.

"It's just a smile on his face, and that's priceless," he said.

"He just forgets the reason why he's in here, and why he's sick, and as a parent it's magnificent."

The clown doctors have visited the Royal Hobart Hospital more than 1,000 times since 2004, delivering a decade-long dose of the best medicine.

Clown doctors cut the birthday cake to celebrate 10 years of fun. ( ABC News: Lauren Day )

The clowns are generally actors trained to work in hospitals.

They parody the hospital routine to reduce the trauma children often experience.

The clowns use oversized medical equipment, red-nose "transplants", "cat" scans, humour checks and funny bone examinations.

The clown doctors are provided by the non-profit Humour Foundation, which was started by the late Dr Peter Spitzer and performer Jean-Paul Bell in 1997.