Nguyen Thuy Mui, 48, and Nguyen Quoc Truong, 43, were detained Monday after the two tigers were confiscated, the Thanh Nien daily report said.
Police found the animals sedated in the car en route from the capital, Hanoi, to nearby Ha Dong City. Police later discovered four frozen tigers in Truong's house, the biggest one weighing 330 pounds.
Truong told police he had bought the tigers from a Hanoi zoo. The animals were to be processed into expensive traditional medicines that many believe will cure a number of ailments, the newspaper said.
Ngo Ba Oanh, the director of a rescue center in Hanoi, told The Associated Press that the tigers were in good condition.
Mui apparently raised the two live tigers from cubs in her house after buying them six months ago for $14,600. She agreed to sell them to Truong for $40,000.
Vietnam's tiger population has dramatically declined since the Vietnam War ended in 1975 because of shrinking natural habitats and poaching.
About 100 tigers live along Vietnam's borders with Laos and Cambodia, down from thousands before the end of the war, according to the Forestry Department.
