A Ho Chi Minh City court Tuesday sent 52 people to jail and gave seven others suspended sentences for involvement with the Philippines-based M88, one of the world's biggest online casinos.
Six of the accused, who were the site's agents in Vietnam, were sentenced to two to seven years in prison for "organizing gambling".
The rest were found guilty of "gambling", with 46 getting terms ranging from one and a half to four years.
Nguyen Vo Hoai Tram, believed to be the mastermind behind M88's operations in Vietnam -- where gambling is illegal -- is still at large along with several other suspects.
According to the indictment, Tram was the representative of M88, which offers sports betting and other gambling services in many Asian countries.
Through Tram, who was then the director of Hanoi-based media company News Plus, in 2010 his deputy Cu Thi Thanh Hai, Nguyen Le Sang, then deputy director of PR and marketing at Vietnam International Bank, and four others became the website's agents.
Their job was to open personal bank accounts, including in the name of their relatives, to obtain money from gamblers and send to winners.
When their operations were busted in early 2013, their illegal activities were worth VND2 trillion (US$91.63 million), prosecutors said.
In recent years the government and many lawmakers have been considering legalizing sports betting.
Meanwhile, luxury casinos have been springing up around the country to cater exclusively to foreign nationals.