Police in Hamilton are asking Frankton residents to look out for the weapon used to stab a woman in the back at a party on Saturday night.
A man was arrested after the incident.
But the police say a weapon, believed to be a knife with a small silver blade, has not be found, and may be hidden somewhere along with clothing.
Detective Senior Sergeant Andy Bu Bear says notices have been dropped in letter boxes, appealing for witnesses, and asking people to look out for weapons and the clothing.
A scene examination is underway, and a car found to have blood in it, has been removed from the Primrose Street address, where the attack took place.
The injured woman has been interviewed by the police in Waikato Hospital.