A 51-year-old Waihī man was flown to Tauranga Hospital in critical condition on Sunday evening.
Police said on Monday that it was their understanding the man suffered a fall, after which a dog attacked him.
According to the Trustpower TECT Rescue Helicopter website they were called to Waihī where a man was bitten in the face by his dog, sustaining serious injuries.
The man was flown to Tauranga Hospital for immediate medical attention.
Emergency services were called to Consols St in Waihī about 5.45pm on Sunday.
Two ambulances and one helicopter attended. A woman who lived in East Waihī said she heard the helicopter land but did not hear it take off again and assumed it had been there for a while.
Inquiries were ongoing to establish the full circumstances.
On Monday afternoon, the man was transferred from Tauranga to Waikato Hospital.
A Waikato District Health Board spokeswoman said today the man remained in the ICU at Waikato Hospital.