Emergency services were called to a property on Adams Street in St Albans after a man visited the address with a stab wound to his back about 8pm.
The man in his 30s was taken to hospital with non-life-threatening injuries.
Police are yet to establish where or how the man obtained his injuries and the investigation is ongoing.
Anyone who witnessed the incident or has information is urged to contact Crime Stoppers on 1800 333 000.
