The Global Fund to fight AIDS, Tuberculosis and Malaria said it estimated $87 billion was needed to "provide essential services for effective treatment ... to vulnerable populations."
The battle against AIDS alone will cost some $58 billion in 2014-16, it said, with tuberculosis needing $15 billion and malaria $14 billion.
"Today, we have a historic chance to control completely these diseases. If we do not take it, the long term cost will be colossal," Global Fund head Mark Dybul said.
If all the funding is provided, it will be possible to treat some 17 million tuberculosis patients and to prevent millions of new AIDS and malaria cases each year, the group said.