Two secondary schools praised for turning round their GCSE performances this year removed 62 pupils between them before the summer exams, The Birmingham Post can reveal.
Some of the teenagers considered unlikely to achieve good results were referred on to colleges, in some cases expelled, while others had moved out of the catchment area.
One of the schools took more than a quarter of the pupils eligible for GCSEs off its roll while the other expelled a total of 12 pupils between September 2004 and January 2005.
It also emerged that at one of the schools more than half of the grades included in the GCSE figures were in vocational GNVQ subjects.
Birmingham's education authority - which this year achieved a record 56 per cent of 16-year-olds gaining at least five good GCSEs - said the schools "needed to weed out any difficulties" as quick as possible.
But the city's head of education scrutiny said the move to omit pupils "raised questions" about the placing of some schools in the league table.
At Kings Norton High the pass rate for pupils gaining five or more A* to C grade GCSEs more than tripled from 16 per cent in 2003/04 to 50 per cent for 2004/05.
However, the school removed 36 of the Year 11 pupils, who sit GCSEs, between September last year and January 2005.
The College High School in Erdington almost tripled its pass rate from 12 per cent in the previous academic year to 34 per cent this year. It took 26 pupils off roll during the same period.
Neither of the schools was available for comment last night.
But Jon Hunt (Lib Dem Perry Barr), head of Birmingham's education scrutiny committee, said: "It does raise questions.
"Clearly these two schools have had to grapple with a lot of issues to pick themselves up off the floor. But I would like to have more explanation about it."
Birmingham City Council confirmed that, once taken off roll, youngsters did not factor in a school's final pass rate.
Out of the 36 pupils removed from the 130 who were eligible for GCSEs at Kings Norton High in September 2004, 28 were referred on to colleges for alternative educational provision.
Five moved out of the area, two were "untraceable" and one was permanently excluded.
Information released by Birmingham's Education Department yesterday also show more than half of the grades at Kings Norton High - 55 per cent - were achieved in vocational GNVQ subjects.
The exams, where pupils can pick up the equivalent of four GCSEs in just one subject, have been criticised as an easier option, though this was rigorously denied by the authority.
At The College High, 14 out of the September 2004 total of 150 GCSE pupils were moved into alternative provision and 12 permanently excluded. Its percentage of grades that were in GNVQ subjects was 17 per cent.
On the issue of taking pupils off roll, a spokesman for Birmingham's education department said: "It is the schools' decision."
He said Kings Norton High had just received a glowing Ofsted report that found it had no areas in which it needed to improve.
"The school needed to weed out any difficulty."
Announcing Birmingham's improved performance, Les Lawrence (Con Northfield), cabinet member for education, said: "The College High is one example of the way schools in the city are showing when you have the right relationship between staff, pupils and parents, then success follows."