Two HIV positive patients in the United States have been taken off their medication after bone marrow transplants seemed to have cleared the virus from their bodies.
One of the patients has spent nearly four months without taking medication with no sign of the virus returning.
But the medical team at Brigham and Women's Hospital in Boston caution that it's far too soon to talk about a cure.
Their findings were presented at the International Aids Society Conference.
The BBC reports the two men, who have not been identified, had lived with HIV for about 30 years.
They both developed a cancer, lymphoma, which required a bone-marrow transplant.
Bone marrow is where new blood cells are made and it is thought to be a major reservoir for HIV.
After the transplant, there was no detectable HIV in the blood for two years in one patient and four in the other.
The pair came off their anti-retroviral drugs earlier this year. One has gone 15 weeks, and the other seven, since stopping treatment, and no signs of the virus have been detected so far.
"What we can say is if the virus does stay away for a year or even two years after we stopped the treatment, that the chances of the virus rebounding are going to be extremely low,'' Dr Timothy Henrich told the BBC.
"It's much too early at this point to use the C-word (cure)."