Vietnam's central bank set the reference rate for the USD/VND rate at 21,890 on Wednesday, up 0.99% on Tuesday's rate.
The State Bank of Vietnam also widened the trading band for the USD/VND to 3% per day, from 2% previously. The trading band was widened from 1% to 2% last week.
The move comes just over a week after China made a similar move with the Yuan, following a sharp drop in exports in July. The Yuan was devalued almost 3% in total last week.