A woman working as a judge at a dog show has been badly injured after falling on stairs from the judges' box.

The 35-year-old, from Te Awamutu, has serious head and chest injuries from her fall this afternoon.

The Waikato Westpac Rescue Helicopter was sent to a farm just south of of Ohura, near Taumarunui, about 3.30pm.

A dog trial event was underway at the time and the woman was on the judging panel.

She was airlifted to Waikato Hospital where she's undergoing treatment.