Governments of the 13 countries where tigers still live aim to agree moves that could double numbers of the endangered big cats within 12 years.
The International Tiger Conservation Forum in St Petersburg will discuss proposals on protecting habitat, tackling poaching, and finance.
About 3,000 tigers live in the wild - a 40% decline in a decade.
There are warnings that without major advances, some populations will disappear within the next 20 years.
Five prime ministers are due to attend the summit, including China's Wen Jiabao and Vladimir Putin of Russia.
"Here's a species that's literally on the brink of extinction," said Jim Leape, director general of conservation group WWF.
"This is the first time that world leaders have come together to focus on saving a single species, and this is a unique opportunity to mobilise the political will that's required in saving the tiger".
BBC News
