UN Secretary General Ban Ki-moon has called for global action to end the Aids disease by 2020.
"That is our goal - zero new infections, zero stigma and zero Aids-related deaths," Mr Ban said at a UN summit on Aids in New York.
The three-day meeting marks the 30th anniversary since the discovery of HIV - the virus that leads to Aids.
Meanwhile, African leaders called for greater resources to battle the pandemic across the world.
Some 34m people have Aids, but about half of them do not know they have the disease, according to the UN.
"Today, we gather to end Aids," Mr Ban said at the opening of the United Nations General Assembly meeting on Wednesday.
"If we are to relegate Aids to the history books we must be bold. That means facing sensitive issues, including men who have sex with men, drug users and the sex trade," the UN chief said.
Mr Ban stressed that new infections have dropped by 20% since 2001 - the year when world leaders first pledged to act to control the pandemic.
He also urged the global community to "come together in global solidarity as never before" to achieve universal access to Aids treatment by 2015 and also efforts to lower costs.
The meeting is being attended by 30 presidents and heads of government, and some of the African leaders spoke of the desperate need for more funds to fight the disease.
"To say that adequate funding is critical to the success of our HIV and Aids response is an understatement," said Nigerian President Goodluck Jonathan, whose country has the highest number of HIV-positive people after South Africa.
Gabon's President Ali Bongo Ondimba said that resources available for Africa "remain insufficient given the size of the HIV/Aids impact on the continent".
More than 9m people still do not get retroviral treatment to keep HIV/Aids at bay, and an estimated 1.8m people die each year from Aids.