Around 100 students across the Forest could have missed out on a vital GSCE pass in English because of a national marking fiasco.
Secondary schools across the Forest are appealing amid allegations that children taking the exams in June were deliberately downgraded by the exam boards.
An inquiry is under way after exam regulator Ofqual admitted grade boundaries were lifted sharply between English exams sat in January and those sat in June.
Teachers believe many children awarded a D would have previously received the C grade normally needed for sixth forms, colleges and apprenticeships.
Nobody knows how many children in the Forest have missed out but staff at Beacon school Dene Magna say they are appealing on behalf of 24 youngsters who should have got at least a C or above.
Other grades would have risen because of the changes, but dropping below a C is the main issue.
Headteacher Stephen Brady said: "The results for English were not in line with other subjects and, upon investigation of the changes, we will be appealing."
Wyedean head Clive Pemberton says his school plans to take action and other Forest secondaries are believed to be doing the same.
Whitecross have put a statement on the school website telling parents: "We are following this issue very closely and are making enquiries on behalf of students to ensure that their English results are accurate and fair.
"We will notify individual students of changes as soon as possible."
Some local authorities are threatening legal action but a spokesman for Gloucestershire said: "The issue is not a county council matter and any potential action would have to be taken independently by the schools involved."
But Gloucestershire College executive director Peter White said pupils who missed out will not be turned away.
"Each applicant is offered a course at a suitable level, and has the opportunity to study towards key skills in English, Maths and ICT alongside their course if appropriate.
"As a result of the current GCSE inquiry, we have introduced our own 'English skills check' for those who have fallen short of the required English GCSE grade for their course. Where appropriate, a student may then be able to study a fast-track GCSE level English course alongside their chosen course."