Nicole Kidman and Keith Urban have cheered up sick kids at an Australian hospital with a singalong on a recent visit.

The Grace Of Monaco star and her country singer husband performed Amazing Grace at the Monash Children's Hospital in Melbourne, and left behind a signed acoustic guitar as a gift ahead of a charity ball.

A video posted online shows Keith strumming his guitar in a corridor while Nicole and all the staff gather round and sing along.

A message on the hospital website said: "Friday 13 June 2014 proved to be a very lucky day for the children at Monash Children's Hospital who were visited by very special guests; Nicole Kidman and Keith Urban before they attended the Swisse Wellness Australia Celebrate Life Ball.

"Keith bought his guitar along and sang a heartfelt rendition of Amazing Grace to the patients, families and staff at the Neonatal Intensive Care Unit. He had some extra help with vocals thanks to Nicole and of course our incredible NICU staff. We want to say a huge THANK YOU to Nicole, Keith and Swisse for lifting up the spirits of some our most deserving patients, families and staff."

The star couple donated an acoustic guitar to the neonatal unit, signed: " With love Keith Urban and Nicole Kidman."