The Labor newspaper quoted a report by the Ministry of Education and Training as saying that only 67.5 percent of the students passed their graduation exams, down from 92 percent last year.
The southern commercial hub of Ho Chi Minh City had the highest success rate, with 95 percent of its students passing the exams. Hanoi, the Vietnamese capital, ranked fourth with 86 percent.
The northern province of Tuyen Quang finished at the bottom of Vietnam's 64 cities and provinces, with only 14 percent of its students passing the exams, the newspaper said.
Ministry officials were not available for comment Monday.
The government declared a war on cheating last year, after a teacher from northern province of Ha Tay said that cheating was widespread at his school, a disclosure that was widely covered in the state media.
The ministry sent some 6,000 officials on inspection missions to police the national graduation exams taken in late May.
The roughly 320,000 students who failed their exams will retake them in late August, the newspaper said.