A 61-year-old from the central province of Quang Tri is sitting for the college entrance exams on Monday and Tuesday, local news website VnExpress has reported.
Nguyen Van Minh is taking the exam for admission to the Physics Faculty at the School of Science in Hue University.
Minh told the newswire he had failed one exam in 2008 and quit another in 2010 due to toothache.
His family has tried to prevent him from sitting for the exam again, but they have not been able to stop him.
Minh got on his motorbike at 4 a.m. on Monday and arrived at the university just in time to take the exams without having any breakfast.
"I've done so-so on Math and hope that I'll pass," Minh told VnExpress. "Otherwise I will continue until I pass."
Minh had graduated from Hue Education University and been a teacher for 12 years. He retired in 1988 due to bad health.
Two of Minh's children are graduates and another one is in his last year at the Da Nang Polytechnics University.
The Ministry of Education and Training does not prescribe an age limit for writing the college entrance exam if the candidate has a high school graduation degree.
College entrance exams in Vietnam require students to answer questions in three subjects, depending on which college they have registered for.
Students taking the Math, Physics and Chemistry group will have their exams on July 4 and 5.
Those taking the Math, Chemistry and Biology; or Math, Literature and English/French; or Literature, History and Geography groups would do so on July 9 and 10.