The man, who is in his 20s, alerted the police himself just before 3 o'clock after the incident that took place on Storgatan in central Västervik.
When the ambulance and police arrived at the scene, the man must have cuts on his body.
- He must have received injuries with a stab wound, says Evelina Olsson, press spokesperson at Police Region South.
During the night, a number of witnesses from the scene have been heard, and a suspected crime scene has been cordoned off.
The police write on their website that the suspected perpetrator, who they are now looking for, must have been unknown to the victim.