An ambulance was called to the scene in Balfron Loan, Edinburgh, this morning and she was pronounced dead.
The death is being treated as unexplained and police appealed for information.
A Police Scotland spokesman said: "Police in Edinburgh responded to an address in Balfron Loan at around 7.30am on Thursday 13th February after a woman was found lying unconscious within a garden.
"She was subsequently pronounced dead by ambulance staff before being taken to hospital.
"Inquiries into the full circumstances surrounding this incident are ongoing and anyone who can assist officers with their investigation is asked to come forward immediately.
"The woman's death is being treated as unexplained at this time."
A post-mortem examination is to be held and police are appealing for anyone who saw anything unusual in the area last night or early this morning to contact them.
The woman is still to be formally identified, police said.
Detective Chief Inspector Keith Hardie said: "We are treating this death as unexplained, pending the results of a post-mortem examination, which will be carried out in the next day or so.
"I would appeal to anyone who saw or heard anything unusual in the area last night or this morning, or who has any other information which could help us, to contact Police Scotland on 101 or through Crimestoppers on 0800 555 111."