The Higher English exam is to be reviewed following complaints that it is narrow and unreliable.
Schools said some high-performing pupils had failed to pass the exam
The Scottish Qualifications Authority has come under criticism from schools after a survey among headteachers revealed widespread unease.
They said some candidates predicted to do well in the exam were not passing or passing with disappointing grades.
The SQA has agreed to review the exam's content but will also give schools a better idea of what examiners want.
This will enable teachers to be better placed to predict candidates' grades and help them pass.
Teachers and headteachers had also complained that the exam was too limited - for example, while creative writing features in the Higher course, there are no marks for it in the exam.
The review was announced following a meeting between the SQA, the Headteachers' Association of Scotland (HAS) and the Scottish Council of Independent Schools (SCIS).
Higher English was introduced as part of Higher Still in 1999.
It was reviewed and modified in both 2000 and 2003 in response to the concerns expressed by the teaching profession over assessment and workload issues.
The SQA said it had been monitoring the qualification and working with the teachers and headteachers to understand how it has been performing.
The SQA said it was taking steps to reinforce high standards of marking for all qualifications, particularly as a number of technical issues were raised around the marking scheme that has been in place for Higher English since 2003.
A spokesman for HAS said: "The issue of Higher English was raised with SQA in October following concerns raised by members over inconsistencies in results attained by students.
"HAS is pleased to be able to confirm that the issues raised have been fully examined by SQA and pathways forward presented.
"SQA has also indicated that these issues were in line for examination as part of the work required for A Curriculum For Excellence and that developments required will fit in with this work in coming months."