The researchers in Berlin said the man, who suffered from leukaemia and HIV, had shown no sign of either disease since the transplant two years ago...
Berlin's Charite hospital said the 42-year-old patient was an American living in Berlin who has not been identified.
He had been infected with the human immunodeficiency virus that causes Aids for more than a decade and also had leukaemia.
The clinic said since the transplant, tests on his bone marrow, blood and other organ tissues have all been clean.
"More than 20 months after the successful transplant, no HIV can be detected in the patient," the clinic said in a statement.
But leading HIV researcher, Dr Andrew Badley, of the Mayo Clinic in the American state of Minnesota, has warned a lot more tests are needed to prove the man is clear of HIV.Roughly one in 1,000 Europeans and Americans have an inherited genetic mutation, which prevents HIV from attaching itself to cells.
This is very promising research. If the patient is finally proven to be completely and permanently free of the HIV virus then a cure is upon us. The only possible kink in this cure is the relative scarcity of donor individuals with the genetic mutation that causes them to have a natural resistance to HIV. Hopefully the researchers will find a way in time to replicate this mutation without a donor.
Cross your fingers every one and keep an eye on this story, a new day in medicine may be dawning.