The 44-year-old, of west London, passed out as she was nearing orgasm and scans later revealed a blood vessel had burst inside her skull.
Despite only suffering a 'moderate' headache when she came round after three minutes of unconsciousness, she was taken to A&E in an ambulance.
Medics didn't directly explain what caused the stroke - but said changes in blood pressure during s-x are 'well-described' as a cause of bursting blood vessels.
The unnamed woman was treated at West Middlesex University Hospital in Isleworth, in the London borough of Hounslow.
Her partner, whose s-x is unknown, said they noticed 'her body was stiff' when they were performing oral s-x on her.
Doctors recording the woman's case wrote in the medical journal BMJ Case Reports: 'On closer history taking, the patient reported nearing orgasm while receiving oral s-x from her partner before losing consciousness.'
They added: 'She had been otherwise well preceding the event.'