The pair, who have not been named, were caught with 3.5 kilograms of heroin in hidden compartments in their luggage at Ho Chi Minh City airport, a policeman with the anti-drug squad said on Wednesday.
Further details about the suspects, aged 31 and 24, have not been released.
The heroin was hidden in 11 packages which had been treated to avoid detection by sniffer dogs, the state-run Thanh Nien newspaper reported.
The Australian embassy in Hanoi did not respond to a request for comment.
Vietnam takes a hardline on drugs and anyone found guilty of attempting to smuggle more than 600 grams of heroin or cocaine can face the death penalty.
Convictions and sentences are revealed only by local media which is strictly under state control.
Foreigners frequently fall foul of the nation's stiff drug laws.
In August this year, a Thai woman was sentenced to death for smuggling two kilos of cocaine.
The same week, a 31-year-old Nigerian man was sentenced to death for smuggling 3.4 kilos of methamphetamine from Qatar.
Vietnamese authorities have seized more than 24 kilos of drugs at Ho Chi Minh City airport this year, the Thanh Nien daily said.
On Sunday, a 26-year-old Chinese woman, identified as Li Chunying, was arrested with 2.2 kilos of methamphetamine.
