Exports fell 8.3 percent from the second half of November to $12.28 billion, with a double-digit drop in smartphones, machinery-equipment, steel and vehicles, according to Vietnam Customs.
In the same period, imports rose 3.6 percent to $13.17 billion, with a double-digit increase in machinery-equipment and vehicles.
But from the beginning of the year until December 15, the country had still recorded a trade surplus of $19.18 billion, a record high.
During this time, the country's trade value, calculated by combining exports and imports, rose 4.5 percent year-on-year to over $515 billion, two-thirds of which came from foreign direct investment.
Last year, trade value reached $517 billion for the first time, with Japan, the U.S., E.U. and ASEAN the biggest export markets.