A 21-year-old man was attacked while walking close to University Metro station, off new Durham Road, shortly before 1.45pm yesterday.
The victim was taken to Sunderland Royal Hospital for treatment to wounds in his neck, believed to be caused by a knife.
Police have arrested a 32-year-man in connection with the assault, on suspicion of wounding with intent to commit GBH, and say he is helping them with enquiries.
The 21-year-old has been released from hospital.
The area around University Metro station was cordoned off yesterday as police launched their investigations.
Enquiries are still ongoing, and officers are out and about in the area.
Police have stressed that such attacks are uncommon, but anyone concerned should get in touch.
Anyone with information about the assault is also asked to contact police on the non-emergency number 69191 ext 101, or Crimestoppers anonymously on 0800 555 111.