The girl, who had defied police orders to do so, had just watched her mother emerge from the burning building, injured and distraught.

This single-minded act of selflessness not only saved Zachary Quilliam but earned his sister a Tasmania Police certificate of high commendation, which was awarded at Smithton yesterday.

After the handover, Melissa said Zachary was like most little brothers, getting on her nerves occasionally.

Like any nine-year-old, Zachary has a cheeky streak and boundless energy.

But she cannot imagine life without him.

It was five years ago when Melissa rushed to save Zachary from their burning home.

At 7am, when the smoke detectors first sounded at the Quilliam's Smithton home, Melissa's mother, Sandra, frantically shepherded her family from the burning building.

It was not until they were outside she discovered her son was missing.

The fire was so intense, firefighters were prevented from accessing the building and so it seemed Zachary was trapped.

But Melissa would not rest until she knew her brother was safe.

Before anybody could stop her, she raced towards the building and disappeared into the flames.

"I was so focused on getting Zach out, I wasn't thinking of anything else," she said.

"All I can remember is hearing him screaming out for Mum and I followed the sound until I found him."

Melissa's act of bravery has earned her several medals since, including the 2007 Clarke Medal from the Royal Humane Society, presented to her by Governor-General Michael Jeffery.