The Secondary Heads Association has accused the Government of using a discredited benchmark of GCSE success and called on ministers to reform league tables.
SHA is opposed to the publication of the percentage of 16-year-olds with at least five C grades.
Instead, it wants the average point score in the best seven subjects to be published for the year cohort.
John Dunford, SHA general secretary, said: "The five A*-C measure reflects the performance of only a proportion of young people and gives no credit to the school for raising a pupil's achievement from grade A to A*, or E to D. It gives no recognition at all for achievement below grade C, which demotivates many pupils."
SHA also recommends that the new Certificates of Achievement, which reflect performance below grade G, should be included in the league tables.