Surgeons at a clinic in a Cleveland, Ohio, have performed America's first almost-total face transplant.
The reconstructive surgeon in charge of the operation - Dr Maria Siemionow - replaced 80% of a woman's face with that of a dead female donor.
The patient's name and age have not been released.
The Cleveland transplant is only the fourth to be carried out. Two operations have been conducted in France and one in China.
The world's first face transplant took place in France three years ago, on Isabelle Dinoire, a woman who had been mauled by her dog.
Surgeons used donor tissue to replace her nose, mouth, lips and chin.
Two other such operations have been carried out since then - one on a Chinese farmer who was mauled by a bear while trying to protect his sheep, and the other on a French man who had become disfigured by a genetic condition.
Doctors in Cleveland said the operation had been carried out two weeks ago and they would release more details on Wednesday.
After the procedure, all patients have to take medication for the rest of their lives, which suppresses their immune system to prevent the transplanted skin being rejected.
The new face does not look like the donor because its shape is altered by the muscles and bones of the patient's face.
The Frenchwoman who had the first transplant has said she is satisfied with the results.
But some experts warn of possible psychological side-effects which may include remorse, disappointment, or grief and guilt towards the donor.