Italian neurosurgeon Sergio Canavero says he'll conduct the first-ever head transplant next year, and he's already got a patient lined up.
But Otago University Neuroscience Professor Dirk De Riddler says most doctors aren't optimistic about the procedure.
"Canavero thinks we're more ready than most of us would be willing to accept," he says.
Science has already pulled off some triumphant transplants.
In the 1950s a Soviet scientist fused the head of a small dog onto a larger one.
Both dogs could see and move, but died soon after.
After losing his hands and feet at age two, US boy Zion Harvey became the first person to receive a double hand transplant last year.
Now he can write and even throw baseballs.
In 2005 a French woman recieved the world's first partial face transplant.
Isabelle Dinoire underwent the surgery after being mauled by her dog.
Several full face transplants have been successful since then.