An independent investigation has been launched by the Scottish Qualifications Authority after a Higher exam in mental health care, offered at 18 further education colleges, produced an exceptionally low pass rate this summer.
The course, sat this year by 423 FE students - in most cases as part of an access to nursing study programme - had a pass rate of only 35.9 per cent compared to last year's 63.7 per cent when it was sat by 405 candidates.
Of the 423 candidates who sat the exam, only 152 passed it: 9 gained As, 36 a B and 107 a C. A further 67 were awarded a D and 204 candidates received no award.
Initial inquiries by the SQA showed no discrepancies in its marking procedures.
The course has been offered since 2004, but SQA officials became concerned by the "significant drop" in the pass rate this summer.
"Due to our concerns, we fast-tracked the formal appeals process, during which we had another opportunity to verify marking procedures and ensure that they met the high standards of our existing quality assurance measures," said an SQA spokesman.
He added: "Because the appeals and quality assurance process did not bring to light any fundamental strategic or systemic reasons for this year's exceptionally poor pass rates, we decided that we should put in place an independent review process."
A review team, chaired by Ken Cunningham, general secretary of School Leaders Scotland and a member of the SQA qualifications committee, has now been asked by the SQA and Scotland's Colleges to try and identify the reasons behind the drop.
The review is expected to reach its conclusions by the end of this month.