The Edexcel exam board said it had received a flood of enquiries from the independent sector after launching its new "international" GCSE last month.
The schools' interest comes amid continuing controversy over coursework. Critics say it is too easy for GCSE students, or their teachers, to cheat and that coursework places too great a burden on staff.
The international GCSE, is being offered in 10 subjects, and is intended for overseas students.
An Edexcel spokeswoman said the number of schools starting international GCSE courses this year was fairly low. Some 20,000 students will sit the exams in 2004-5, in Britain and overseas.
The exams are being offered in: English literature, English language, maths, physics, chemistry, biology, information and communications technology, business studies, history and geography.
There were 5.7 million British entries for conventional GCSEs this summer.
The University of Cambridge Local Examinations Syndicate has been offering international GCSEs for 15 years. These are taken mainly overseas.
State schools have to offer mainstream GCSEs and there appears to be no immediate prospect of a cut in coursework for their pupils.
However, Mike Tomlinson - who is leading a government task force investigating replacing GCSEs and A-levels with a baccalaureate-style diploma (see report above) - believes pupils do too much coursework. It may become less important in any future 14-19 exam system.
Geoff Lucas, secretary of private schools' body the Headmasters' and Headmistresses' Conference, said he could not comment on the detail of the new qualification. But he said: "There's no doubt that the feeling within HMC, and I think also the country at large, is that coursework has had its day in its current form.
"We hope that Tomlinson will look at it and that it will be dealt with as part of changes to mainstream qualifications."