More than a third of Standard Grades and Advanced Highers have been added to the list of Scottish examinations under threat, it has emerged.
A number of Higher exams failed to attract a single pupil
The Scottish Qualifications Authority is also considering ditching dozens of Higher subjects as part of a review.
The courses which could be lost are those sat by small numbers of pupils.
However, the SQA stressed it was not simply a matter of "number crunching" and said less popular subjects could be saved if a strong case was put forward.
BBC Scotland's education correspondent, Seonag Mackinnon, said the proposals to axe exams were more wide-ranging than it first seemed.
The SQA is currently developing a policy on low and no-uptake subjects.
This year 28 of the 103 Highers on offer failed to attract a single student, while a further 35 were sat by fewer than 100 students.
It emerged on Friday that the SQA was planning to write to schools and colleges to warn them that some of the less popular Higher subjects were under threat.
The authority said any decisions on the future of such courses would only be taken after a process of consultation.
It has now emerged that the future of some Advanced Higher subjects - including languages, home economics and psychology - are also in the balance.
Sixteen of the 42 Advanced Highers are under review, along with 23 of the 67 Standard Grades.
Supporters of threatened subjects can appeal, but will have to argue they are important to Scotland's culture or economy.
SQA spokesman Mike Haggerty told BBC Scotland that it was five years since the introduction of the Higher Still system.
"We think it is reasonable to keep them under review and to get to a point in the review where we can see what the patterns are," he said.
"This review is all about choice. We do have a number of subjects where the young people of Scotland have shown that they do not want to take these subjects.
"What we have got to do is to recognise that, move on and find ways to give subjects, to give choice that the young people of Scotland want."
He said that the number of people sitting a course was only one of the criteria involved in the review.
"Numbers are a trigger point to start a review, not to finish it," said Mr Haggerty.
"But we also need to make sure that we are touching base with the cultural, educational and social needs of Scotland, that we are giving qualifications and providing skills that Scotland wants and Scotland needs."
He said that subjects could be secured if there was a strong enough case made for them, adding: "It is not just a matter of number-crunching."
Scottish National Party education spokeswoman, Fiona Hyslop, said educational needs should be put before "bureaucracy".
She said: "This is the educational equivalent of putting the cart before the horse.
"While this axing of exams is being presented by the SQA as a simple housekeeping measure, it is worrying that it is coming out prior to the results of the delayed national curriculum review.
"If this is a signal of what is to come then it is of great concern to the SNP as it implies the curriculum review is being driven more by bureaucracy and costs rather than building the sort of education system we need for our children."
But teachers' union The Educational Institute of Scotland (EIS) said cuts were inevitable.
Spokesman George McBride said: "When you look at headline figures saying that half or two-thirds of Highers courses are going to disappear, that does look colossal.
"But we're talking often of courses where sometimes literally there have been no candidates in the last couple of years and others where there have been a handful, five or six candidates."