This is the verdict of a report today by the Royal Society, the world's oldest scientific academy.
Its State of the Nation report on science and maths education shows that the number of 17-year-olds taking biology, chemistry, physics and maths, measured as a proportion of total entries, shrank between 1997 and 2007.
While absolute numbers of students taking biology and chemistry grew over that time, they fell in physics and maths.
The overall number of A-level students rose by 22 per cent over the same period, meaning that in all four there was a drop in the proportion studying the subjects. The number of specialist maths and science teachers has also fallen in 10 years. Professor Michael Reiss, the society's director of education, said: "Science and mathematics education has been assaulted by reform over the last 20 years."
In England there was an increase in the numbers taking all four subjects in this summer's exams.
In Wales, however, chemistry and maths entries increased, but biology and physics entries went down for the second year in a row.
In today's TES Cymru, David Reynolds, professor of education at Plymouth University, argues that Stem subjects - science, technology, engineering and maths - should be the "lifeblood" of schools in Wales as they are directly involved in the wealth creation to build a nation.