Police were called to a report of a man with a stab wound on Raby Road, Hartlepool, at around 2.30am this morning (Tuesday 25th June).
The 30-year-old man was taken to James Cook University Hospital, where he is in a serious condition.
A cordon remains in place on York Road towards the junction of Raby Road, and this is expected to remain in place for some time.
Officers are investigating the incident and anyone with information is asked to contact Hartlepool CID on the non-emergency number 101, quoting event number 106345.
Crimestoppers can be contacted anonymously on 0800 555 111 or www.crimestoppers-uk.org.