A man was stabbed in the chest in the early hours of Monday morning in Clayton-le-Moors.
Detectives believe the 25-year-old local male was stabbed once by a female outside the Volunteer Arms at around 12.30am.
He was taken to Royal Blackburn Hospital, received treatment and has since been discharged.
Police are now appealing for anyone who saw the incident to come forward.
DI Jill Johston, of Accrington CID, said: "No arrests have been made at the moment, however there are positive lines of enquiry on a female suspect who we are tracing.
"If anyone has seen an argument in the street we would like them to contact us on 01254 353741."