The $48bn legislation also lifts a ban on HIV-positive people entering the US
President Bush has signed off a new law that triples America's budget for fighting Aids and other diseases in Africa and the Caribbean.
The new legislation increases US funds to combat Aids, malaria and tuberculosis to $48bn - up from $15bn.
The new law also drops requirements for one-third of Aids funds to be spent promoting abstinence.
Mr Bush won praise for the new law both from human rights campaigners and from opposition politicians in the US.
'Face of compassion'
Earlier this month the Democratic-controlled US congress approved the increased funding for the five-year scheme.
The Democratic Speaker of the House, Nancy Pelosi, described the new package as America's "compact with developing nations across the globe", saying that the new legislation showed "America's true face of compassion".
The law also lifts a ban on HIV-infected people from entering the US - a move which won praise from the rights group, Physicians for Human Rights, and from gay rights campaigners in the US.
About two-thirds of the world's HIV-positive people live in sub-Saharan Africa. The International Red Cross estimates that at least one in 10 people living in countries such as South Africa, Malawi and Mozambique is HIV-positive.
Malaria kills more than one million people every year, according to the World Health Organisation - 90% of them in sub-Saharan Africa.
And in a report earlier this year, the WHO also estimated there were 14.4m cases of tuberculosis worldwide in 2006.