A koala has been caught on camera going for a night-time stroll around a hospital in Australia, checking out the waiting room and emergency department.

The koala, who has been named Blinky Bill, was picked up by the CCTV at Western District Health Service hospital in western Victoria.

Rohan Fitzgerald told ABC the animal appeared very casual and relaxed as he did the rounds: "He seemed to know exactly what he was doing.

"After about three minutes, at about 3:30am, he investigated sufficiently and made sure everything was in order and then decided to exit the building."

Blinky Bill was filmed on 20 April and the hospital has now posted the footage on its website. The film has become an overnight sensation with thousands of views from across the world.

Hospital staff saw the koala but decided to leave him alone. He went through a number of automatic doors, but could not gain access to one so wandered into another room before leaving the hospital.

"Normally we don't have people come into our emergency department that are less than a foot tall," Fitzgerald said.

"He wasn't that obvious to begin with. He entered the doors and they've opened automatically for him and that's come into our waiting room.

"I've heard there have been koalas visiting local homes in the area for a number of years now.

"This is the first instance I've seen a koala come into our hospital. You never know who you're going to see when you come to Western District Health Service."