Harsh and inconsistent marking is putting pupils in England off studying languages beyond age 14, a report says.
The dawn of more rigorous GCSEs will further reduce interest in languages, research by the British Council and Education Development Trust suggests.
It says a focus on maths and sciences, as well as a perception languages are a hard option, is also de-motivating pupils and teachers.
Exams watchdog Ofqual said last year's languages results were "very stable".
From September 2016, new GCSE and A-level modern language syllabuses will be taught in England, and new exams will be taken in the summer of 2018.
The Language Trends Survey, in its 14th year of charting the state of language learning in England's schools, suggests these changes - particularly at A-level - will deter pupils from studying languages.
