Nguyen Phi Hung, 42, Le Hong Hai, 42, Le Ba Thao, 39, and Lau Ba Chong, 24, were arrested in the province's capital town Vinh while carrying the drugs to a transit point.
The gang, led by Hung, would later have delivered them to the south for selling, the police said.
Officers seized 20 kilograms of methamphetamine, 20 kg of ketamine, 6.6 kg of heroin and three cars.
Billions of dong in cash were later seized from Hung’s house in Vinh (VND1 billion = $43,000).
The police are investigating.
Vietnam is a key trafficking hub for narcotics from the Golden Triangle, an intersection of China, Laos, Thailand, and Myanmar.
Those convicted of possessing or smuggling more than 600 grams of heroin or cocaine or more than 2.5 kg of methamphetamine face death. The production or sale of 100 grams of heroin or 300 grams of other illegal narcotics is also punishable by death.