Two nurses waiting in their car before beginning a nightshift at Waikato Hospital fought off a man armed with a knife on Thursday night.
The attack happened at about 10pm.
Waikato District Health Board security manager Dean Ria says the attacker forced his way into the women's car and repeatedly told them to get out while threatening them with a knife.
He says the women fought off their attacker and he fled up Pembroke Street, towards the hospital's main entrance.
The nurses described the attacker as a dark-skinned man of medium height and build aged in his early 20s.
He had shaved black hair and was wearing a red and white patterned bandana over his face.