The entrance exam for US graduate schools is being revamped and expanded after widespread cheating.
Some 500,000 people a year take the Graduate Record Exam in 180 countries.
The test will change in October and will be lengthened from two and a half hours to more than four.
The questions will be used only once and will start at exactly the same time, regardless of time zone, so that students cannot pass on information.
The test will also no longer be offered in a computer-adaptive format, where the difficulty of the test is determined by the candidate's right or wrong answers. Instead, it will be offered in a linear format, in which every student takes the same exam.
The most significant overhaul in the GRE's 55-year history is largely a response to evidence of widescale cheating.
About a quarter of the students who take the test live outside the US, and students in China, Taiwan and South Korea have been caught memorising questions and answers posted on the internet by candidates in different time zones.
Some Chinese organisations are alleged to be hiring people to take digital photos of GRE questions at test centres.
In another scam, Americans used transmitters to convey the test questions to candidates yet to sit the exam.
"The new test will emphasise complex reasoning skills that are closely aligned to graduate work," said David Payne, executive director of the GRE division of the Educational Testing Service, which administers the exam from Princeton, New Jersey.
"We'll include more real-life scenarios and data interpretation questions, and new, more focused writing questions," he added.
Instead of continuous testing, candidates will be able to sit the GRE on 29 specific dates worldwide.
Graduate-school admissions officers will be able to see each student's essay responses on the analytical writing section if they choose.
"These changes are intended to make the GRE a more accurate gauge of how qualified prospective students are to do graduate-level work," Mr Payne said.