The three persons were entering Vietnam in a car when they were stopped by police at the Cau Treo International Border Gate in Huong Son District, Ha Tinh Province.
The drug was packed in paper boxes.
One of the three was Nguyen Quang Trung, a resident of Huong Son. The other two have only been identified as locals from the neighboring province of Nghe An.
The three have reportedly admitted that they were on their way to distribute the drug in Vietnam.
Police are investigating the case.
Vietnam has some of the world’s toughest drug laws. Those convicted of possessing or smuggling more than 600 grams of heroin or more than 2.5 kilograms of methamphetamine face the death penalty.
The production or sale of 100 grams of heroin or 300 grams of other illegal narcotics is also punishable by death.
Although the laws have been strictly enforced with capital punishments handed down regularly, drug crimes remain a serious problem, and transnational drug trafficking in border areas has proved to be a complicated problem with no easy solutions, officials have conceded.