A section of State Highway 2, at Karangahake, was closed for more than seven hours after a crash critically injured two people and seriously injured another.
Emergency services were called to the two-vehicle collision, between Paeroa and Waihi, about 3.15pm Thursday.
A St John spokesman said two ambulances and three helicopters were sent.
St John treated three patients who were airlifted to Waikato Hospital - two in a critical condition and one in a serious condition.
A person with minor injuries was taken to Thames Hospital.
