Some schools have been accused of putting their league table rankings ahead of what is right for their pupils.
Nick Seaton, chairman of the Campaign for Real Education, said there appears to be many schools encouraging students to take exams in softer subjects, rather than traditional subjects such as maths, French and German.
He claimed that schools are taking this route in order to climb league tables and appear more successful.
GCSE results published last week show that the number of pupils obtaining five or more A* to C grades has increased again for the 23rd consecutive year.
"The youngsters who have got good GCSE results deserve full praise and they have obviously worked extremely hard. Having said that, there are huge questions about how the GCSE exam system is working and it really does need sorting out," Mr Seaton commented.
Figures revealed that fewer pupils than ever are studying modern foreign languages, with demand for French falling by six per cent compared to 2009.