The drugs were in cartons under piles of jeans
Police in Vietnam say they have found nearly nine tons of cannabis in a shipment of blue jeans from Pakistan.
The authorities say it is their largest ever drugs seizure - at a value of $90m (£45m).
The drugs, shipped through the port of Hai Phong, were found near the border with China, and are believed to have been ultimately bound for Canada.
Four Chinese citizens and one Indonesian have been arrested in connection with the find.
Anti-drugs police said that the cannabis resin was seized earlier this week on two trucks heading for the Chinese border. It had arrived in April on a ship from Pakistan.
Vietnam has introduced some of the world's toughest drugs laws, and the possession or trafficking of heroin or opium is punishable by death or life imprisonment.
In February a government review of drug-related crimes and trafficking said border provinces had strengthened ties with neighbour countries to fight the transport of drugs.