The United States has lifted a 22-year ban preventing anyone with HIV or AIDS from entering the country.
President Obama says the ban is not compatible with US plans to be a leader in the fight against the disease.
The ban was imposed at the height of a global panic about the disease, at the end of the 1980's.
It put the United States in a group of just 12 countries, including Libya and Saudi Arabia, which excluded anyone, suffering from HIV/AIDS.
An international AIDS summit will be held in the United States in 2012.
The summit was previously impossible to be held there because the ban would have prevented anyone with the condition from attending.
Public health and AIDS experts hailed the announcement.
"It's just not supported by any evidence at this point - whether it was that people were coming into the United States and wildly infecting others or any other sound public health ground on which they could continue to exclude people," said Dana Van Gorder, executive director of Project Inform, an advocacy organisation in San Francisco for people living with AIDS/HIV told SFGate.com.
