Clifford Chance is closing both its offices in Vietnam due to a lack of foreign investment in the country.
A spokesman for the firm says it is likely to shut its practices in Hanoi and Ho Chi Minh City next month.
Clifford Chance has three lawyers based in Vietnam but no partners.
Senior assistant Keith Handley, who was in charge of day-to-day operations, is leaving for an unnamed firm. The remaining lawyers will be moved elsewhere in Clifford Chance's network or sent on secondment to a leading firm in Singapore, says the spokesman.
Clifford Chance opened its Hanoi office in 1994 to handle inward investment work on a wave of optimism about Vietnam's economic prospects. This was followed by Ho Chi Minh City in 1995, when senior partner Keith Clark said: "Our people are very busy in Hanoi on a whole range of work, but we were finding that our clients also need servicing in Ho Chi Minh City."
The spokesman says the decision to pull out of Vietnam is "mainly because the country failed to attract the foreign investment that in the early part of the 1990s commentators said it was going to attract.
"The country's economy has been very slow in developing, and we take the view that the long term prospects are not favourable".
He adds that Clifford Chance will continue to do work in Vietnam. "We have developed pretty good contacts with local lawyers in Vietnam so our interest will remain there.
"We have got good links with the government there and with other governments around Asia so we are able to keep that bridgehead open."
Other western firms with offices in Vietnam include Freshfields, Lovells and Coudert Brothers.