One in seven pupils on a Government scheme to help the brightest children are not getting five good GCSE grades, official figures showed.
Government data on the Gifted and Talented programme shows that in 2007, 11,628 pupils - a total of 14.3% - did not get five A*-C's, including English and maths.
Shadow children's secretary Michael Gove, who obtained the figures through a parliamentary question, said they highlighted a problem with the scheme.
He said: "Far from delivering personalised learning, which tailors each pupil's education to their needs, the Government has failed on the most basic level to ensure teaching by ability."
The Gifted and Talented initiative was set up with the aim of nurturing the ability of England's most able children.
Every state primary and secondary school in England is supposed to identify their brightest and best pupils.
"Gifted" is usually defined as the top 10% of the school population in terms of academic subjects, while "talented" is defined as the top 10% in other areas, such as sport or the arts.
Pupils identified for the programme qualify for extra teaching and support on their particular subject.
A spokeswoman for the Department for Children, Schools and Families said that not all students on the scheme were identified as "academically gifted". Around half have talents that lie elsewhere, such as in sport, art and music.
She said: "Were we to define schools' gifted and talented populations entirely in terms of attainment, that would inhibit schools from identifying underachievers with potential, particularly those held back by disadvantage, so hindering efforts to improve social mobility."