Teachers at two schools in Bolton say they are chasing the exam board Edexcel for guidance on when the results will be ready - but say they have yet to receive a good explanation.
Geoffrey Webster, the exams officer at Smithills School in Bolton says 180 children are still waiting for results there.
"The children are very upset. Some are waiting for interviews for college and need to know their grades," he said.
"Some took the exam a year early - in year 10 - and they are especially excited about finding out.
"I've not come across a problem like this in the past 10 years."
At Canon Slade School in Bolton, 28 children are also waiting anxiously for their maths results.
Director of studies and exams officer Stephen Brierley says the situation is very bad.
"I think we have been treated fairly badly by the examination board.
"We've had phone calls and they have suggested reasons for the delay - but we've had no letter of explanation."
Mr Brierly said he wondered if the papers had been marked in time, because the exam board had run a campaign to find examiners.
Administrative problems
Edexcel say all the papers have been marked and that officials are trying to iron out administrative problems with the schools involved.
They believe the delay involves the tiers or levels of maths papers sat by pupils.
Schools can opt for varying degrees of difficulty on a GCSE maths paper for individual children.
The tiers have variable top marks.
A spokeswoman for Edexcel said: "Our priority is to make sure that every student gets the right grade.
"We are in touch with the schools. These are isolated issues, and generally simple administrative queries to do with tiering and possibly missing coursework.
"When we have clarified the issues we will get back to the schools and issue a grade."