A spokesman for Merseyside Police said the woman’s body was found when officers were called to a house in Folkestone Road, Southport, at 8.40pm on Friday.
A 47-year-old man has been arrested on suspicion of murder.
The force said officers were not looking for anyone else in connection with the incident.
A post-mortem examination will be carried out to establish the cause of death.
Detective Inspector Lee Wilkinson said: “This is a tragic incident and are thoughts with the family of the lady involved.
“An investigation is currently under way and we are carrying out forensic, CCTV and house-to-house inquiries in the local area.
“I would ask anyone who was in the area of Folkestone Road at around 8.30pm last night who saw or heard anything suspicious to contact us as they may have information which is vital to our investigation.”
Anyone with information can call police on 101 or contact Crimestoppers, anonymously, on 0800 555111, quoting reference 21000063162 of January 29.
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