The new rate has been set at VND20,688 a dollar, up VND10 from yesterday.
The central bank has hiked the rate six times this month, each time by VND10.
Banks traded the greenback at the ceiling rate of VND20,895 while on the black market the selling price dropped by VND50 yesterday to VND21,500.
Meanwhile, gold made a U-turn after rising for three days, losing VND200,000 a tael (37.5 grams), following a decline in global prices.
At 8:30am today Saigon Jewelry Co sold the precious metal at VND44 million a tael.
On the Asia market, spot gold dropped by US$14 an ounce this morning compared to $1,666.7.
Gold holdings in the SPDR Gold Trust, the biggest exchange-traded fund backed by bullion, yesterday dropped 0.48 tons to 1,227.51 tons, Bloomberg reported.
Reuters said gold had fallen in tandem with riskier assets Thursday on disappointing economic data from China and weaker US equity markets.
What the stars mean:
★ Poor ★ ★ Promising ★★★ Good ★★★★ Very good ★★★★★ Exceptional