High prices and strong demand for ivory are threatening the survival of the Asian elephant, according to a new study by monitoring network Traffic.
Traffic says that only around 150 wild elephants are left in Vietnam, where booming prices in the illegal trade are among the highest in the world.
This number compares to around 1,000 animals in the 1980s.
Traffic now believes the trade could even be growing in the country, bypassing shops through middlemen or via the internet.
The ivory trade continues despite having being banned by the Vietnamese government in 1992. A loophole means that shops can still sell ivory dating from before this period, and some shop owners allegedly use the rule as cover for restocking with newer pieces.
Illegal tusks are reported to sell for up to US $1,500 per kilo, with cut pieces fetching even more.
Azrina Abdullah, Traffic's Southeast Asia director, told the BBC's World Service of the "major weakness" in the way the Vietnamese Government had implemented its own criminal code, which was revised in 2000.
Ian Redmond OBE, Born Free's senior wildlife consultant and United Nations ambassador for Year of the Gorilla, said he suspected some of the ivory on sale also came from African elephants.
"This is dismal news for Vietnam's dwindling herds of elephant and for all the other species in the ecosystems where elephants are keystone species," he added.
"I wonder how many tuskers survive among the 150 elephants left in Vietnam ? female Asian elephants do not have tusks, and if they only have tuskless males to mate with, there will be fewer and fewer tuskers in the next generation.
"Even if we don?t exterminate these elephants, we are changing them by wiping out the genes for the very feature we most admire ? magnificent tusks."
As part of its commitment to the welfare of elephants in the wild, elephant.co.uk supports the work of TUSK and the Born Free Foundation.
