Surgeons in France have carried out the first face transplant, it has been reported.
The operation lasted several hours
The woman had lost her nose, lips and chin after being savaged by a dog.
In the controversial operation, tissues, muscles, arteries and veins were taken from a brain-dead donor and attached to the patient's lower face.
Doctors stress the woman will not look like her donor, but nor will she look like she did before the attack - instead she will have a "hybrid" face.
It has been technically possible to carry out such a transplant for some years, with teams in the US, the UK and France researching the procedure.
Skin from another person's face is better for transplants as it will be a better match than skin from another part of the patient's body, which could have a different texture or colour.
But the ethical concerns of a face transplant, and the psychological impact to the patient of looking different has held teams back.
Concerns relating to immunosuppression, psychological impact and the consequence of technical failure have so far prevented ethical approval of the procedure in the UK, though doctors here are fully able to perform transplants.
The 38-year-old French patient, from the French town of Valenciennes, underwent extensive counseling before her operation.
The operation took place over the weekend in Amiens, and is believed to have lasted approximately five hours
The French magazine Le Point reports that the tissues, muscles, arteries and veins needed for the transplant were taken from a multi-organ donor in the northern city of Lille, who was brain-dead.
The operations were carried out by a team led by Professor Bernard Devauchelle and Professor Jean Michel Dubernard.
In a statement, the hospital said the woman had been gravely disfigured in the attack in May this year.
She has been unable to speak or eat properly since.
It added that the woman - who wishes to remain anonymous - was in "excellent general health" and said the graft looked normal
Like any other transplant patient, the woman will have to take immunosuppressant drugs to help her body cope with the donated tissue.
Doctors working in the field say many could benefit from the procedure, including 10,000 burns victims in the UK.
Iain Hutchison, an oral-facial surgeon at Barts and the London Hospital, said: "This is the first face transplant using skin from another person."
But there are medical, and ethical, concerns of facial transplants.
Mr Hutchison, who is chief executive of Saving Faces - the Facial Surgery Research Foundation, warned blood vessels in the donated tissue could clot, the immunosuppressants could fail - and would increase the patient's risk of cancer."
Mr Hutchison added there were ethical and moral issues around donating facial tissue.
"Where donors would come from is one issue that would have to be considered.
"The transplant would have to come from a beating heart donor. So, say your sister was in intensive care, you would have to agree to allow their face to be removed before the ventilator was switched off."
Stephen Wigmore, chair of British Transplantation Society's ethics committee, said: "The extent of facial expression which will occur in the long term is unknown.
"The skin tends to promote rejection by the immune system very strongly and immunosuppression is likely to need to be kept at high levels for prolonged periods of time.
"It is not clear whether an individual could be left worse off in the event that a face transplant failed."
Mr Michael Earley, a member of the Royal College of Surgeon's facial transplantation working party, said: "If successful, this is a major breakthrough in facial reconstruction.
"It appears that this has been a partial face transplant incorporating the nose and lips; therefore issues relating to similarity in appearance between donor and recipient are unlikely to be a major problem.
"We wish the patient and the team a successful outcome and look forward to learning more about the details of the procedure which could be a major step forward for the facially disfigured."