Preparation for the crucial exam starts from primary school, and so does the relentless pressure which has been blamed for everything from early burnout and teenage depression to suicide.
Success in the exam -- meaning a secured place in one of South Korea's elite universities -- is seen as the key to everything from future careers to marriage prospects.
With so much riding on the outcome, the day of the test -- simultaneously in 1,257 centres nationwide -- sees the entire country go into "hush" mode.
The transportation ministry bans all airport landings and departures for a 40-minute period to coincide with the main language listening test.
The military also reschedules airforce drills and live-firing exercises and traffic is barred within a 200-meter radius of the test centres.
Public offices and major businesses, as well as the stock markets, opened an hour later than usual Thursday to help keep the roads relatively clear and ensure the students arrived on time.
Anyone who did get stuck could dial the emergency number 112, and request help from police cars and motorbikes on standby to rush them to the centres.
At Seoul's Pungmoon Girls' High School, junior students put up good-luck banners and lined up to shout encouragement as their seniors entered the exam room.
For the equally-stressed parents, for whom their child's result will partly be seen as a mark of their parental aptitude and devotion, there was little left to do.
Mothers, one flicking through her Buddhist prayer beads, prayed outside the Pungmoon school gate, while others went directly to temples in search for some divine intervention.
The approach of the exam day tends to renew a perennial debate in South Korea about the country's obsession with education and the pros and cons of the college entrance system.
The bottom line for many is that the examination itself is fair. Everyone takes the same paper, which relies on the multiple choice system to prevent subjective marking.
Security is absolute, with the hundreds of exam setters sequestered for more than a month in a secret location, which they are only allowed to leave once the test has been taken.
They are kept in total isolation, denied phone contact with their families and with everything down to their food waste subject to rigorous examination.
But if the exam treats everyone equally, critics say preparation favours the rich, and can be ruinous for poorer and middle-income families.
According to the Education Ministry, South Korean parents spent 19 trillion won ($17.5 billion) on extra tuition for their children last year -- equivalent to about 1.5 percent of the national GDP.
Students average five hours sleep a night as the test nears -- a level of physical fatigue that, coupled with the mental anxiety, leads to a discernible spike in suicides around the exam period.
Educational reformers also voice concern over the validity of the exam and the sort of students it produces, pointing to the lack of importance given to creativity or critical thinking.
An editorial in the New York Times on Thursday called the South Korean exam "brutal" and noted that the system goes into reverse after entering college, where graduation is almost guaranteed with even minimal study.
"The paradox is these ridiculous tests don't necessarily lead to demanding college classes," the editorial said.
"Rigorous thinking, reading and writing too often is simply not expected. Doing away with rigid entrance exams is just the first step. What needs to be debated is the quality of education once the students are admitted," it added.