Police were called to a house in Houghton after a pensioner died.
Officers went to an address in Outram Street, close to Houghton Cut, shortly after 4pm on Wednesday.
There, the body of a woman aged 69 was found.
There is believed to be no third party involvement.
A report is now being prepared for Sunderland Coroner’s Office.
A spokeswoman for Northumbria Police said: “At 4.30pm on Wednesday police were informed of the death of a 69-year-old woman at an address in Outram Street, in Houghton.
“There is believed to be no third party involvement and a report will be prepared for the coroner.”
The woman’s name has not yet been released.