The list says the global extinction crisis may be even worse than scientists realise, with "dramatic" declines in many species, including reptiles and primates.
A quarter of the world's mammal species face a high risk of extinction very soon, a conservation group says.
The warning, from IUCN - The World Conservation Union, says an eighth of the world's bird species are at similar risk.
IUCN believes the world should be spending at least 10 times more than it does to halt the slide to extinction.
Over the last two centuries, it says, extinctions have been occurring 50 times faster than the natural rate.
The assessment comes in the 2000 IUCN Red List of Threatened Species, probably the most comprehensive and authoritative inventory of species' global conservation status.
Worse than feared
IUCN is a partnership of states, non-governmental groups and scientific bodies, drawing on the expertise of about 10,000 individual scientists.
The list says the global extinction crisis may be even worse than scientists realise, with "dramatic" declines in many species, including reptiles and primates.
Since the last assessment in 1996, critically endangered primate species have increased from 13 to 19, and freshwater turtles from 10 to 24.
Threatened albatross species have risen from three to 16, because of long-line fisheries.
The total number of critically endangered mammal species is now 180, 11 more than in 1996, while bird species have risen from 168 to 182.
'Jolting surprise'
Those listed as threatened to some degree number 11,046 plant and animal species, in almost all cases because of human activities.
IUCN says this means that 24% of mammals and 12% of birds "face a high risk of extinction in the near future".
The list includes 18,276 species and subspecies. About 25% of reptiles, 20% of amphibians and 30% of fish so far assessed are listed as threatened.
Threatened plants number 5,611, but as only about 4% of the world's described plants have been evaluated the true figure is much higher.
IUCN's director general, Dr Maritta Koch-Weser, said the rise in the number of species at acute risk was "a jolting surprise. These findings should be taken very seriously by the global community".
Poised to disappear
The chair of IUCN's primate specialist group is Dr Russell A Mittermeier, president of Conservation International.
He said: "The Red List is solid documentation of the global extinction crisis, and it reveals just the tip of the iceberg.
"Many wonderful creatures will be lost in the first few decades of this century unless we greatly increase levels of support, involvement and commitment to conservation."
IUCN says human and financial resources need to be from 10 to 100 times greater than they are to tackle the crisis.
It says the rise in the number of threatened primate species, from 96 to 116, owes much to increased habitat loss and to hunting, especially the bushmeat trade.
Gene pools depleted
The rapid decline in tortoises and freshwater turtles in southeast Asia is being caused by "heavy exploitation for food and medicinal use".
Dr Craig Hilton-Taylor, a conservation biologist, is responsible for IUCN's Red List programme.
He told BBC News Online: "One of the priorities is to set far more land aside, to reverse the present deforestation and persuade the logging companies to go for sustainable use.
"But you've also got to take people's needs for food and land into account. If you can get them to appreciate their resources, then green tourism can be a serious part of the answer.
"A lot of species are on the brink, but hanging in there, producing perhaps one offspring every couple of decades - animals like the Sumatran rhinoceros.
"It may take them a long time to vanish completely. But their gene pools will have been disastrously depleted long before then."