Vietcombank sold the dollar at VND24,800, up 0.04% from Monday.
The State Bank of Vietnam lowered its reference rate by 0.07% to VND23,955.
The greenback dropped 0.39% to VND25,600 on the black market.
It has increased against the dong by 1.56% since the beginning of the year.
Globally the dollar index rose 0.04% to 102.83, having hit a roughly two-month low of 102.33 last week, Reuters reported.
The euro retreated from a roughly two-month high hit last week and last bought $1.0936.
Sterling rose 0.04% to $1.2816, though was some distance away from Friday's more than seven-month peak.