More than a quarter of pupils do not take English literature GCSE
More than a quarter of teenagers in England are not taking English literature GCSE, according to figures published by the Conservatives.
About 37% of poorer students - those entitled to free school meals - did not sit the exam in 2008.
Overall 28% of pupils did not sit the GCSE exam in 2008 - up a fifth from the 23% who did not do it five years ago.
But while the number fell at maintained schools, it rose at independent ones. The Tories said it was "shocking".
Conservative schools spokesman Michael Gove expressed concern that poorer pupils in particular were missing out on the country's cultural heritage.
The figures suggest a growing social gap in pupils learning about literature - as 30% of pupils who had free school meals did not sit the exam five years ago, and that figure has increased to 37%.
In contrast, 19% of pupils not on free school meals did not take English literature GCSE last year, up from 14% in 2003.
However while the number of students doing the exam at maintained schools fell from 481,440 in 2003 to 472,575 in 2008, more youngsters are taking the subject at independent schools.
There was an increase from 35,458 students in 2003 to 38,933 in 2008.
Overall 185,789 15-year-olds did not do the subject in 2008, from a total cohort of 653,808 pupils.
"An understanding and knowledge of English literature is something we would all consider an essential part of education to GCSE level for all pupils," said Mr Gove.
"It is therefore shocking that the subject is in decline to the extent that more than one in four pupils does not even sit it at GCSE."
Schools Minister Jim Knight said: "Michael Gove is talking nonsense."
"Both the English and English literature GCSEs include Shakespeare and other great works of English literature so it's wrong to say that pupils are not reading the classics.
"Last year 96% of pupils sat an exam that included English literature and more young people are achieving the higher grades in English each year," said Mr Knight.
Mary Bousted, leader of the ATL teachers' union, has previously warned that English as a subject is being replaced by "literacy" - with pupils reading extracts rather than complete books.
"I don't want to get misty eyed about the past, but it is clear to me that something important has been lost - for both teachers and taught," she said.
"And that is the heart of the subject - the subject which is dear to my heart - the subject of English."
There have also been fears that the types of subjects and qualifications taken by pupils can be divided by social background - such as modern languages becoming increasingly dominated by pupils in independent schools.